Queen Victoria Victoria (Alexandrina Victoria; 24 May 1819 – 22 January 1901) was Queen of the United Kingdom of Great Britain and Ireland from 20 June 1837 until her death in 1901. Her reign of 63 years and 216 days was longer than that of any previ ...

Frogmore Frogmore is an estate within the Home Park, adjoining Windsor Castle, in Berkshire, England. It comprises , of primarily private gardens managed by the Crown Estate. It is the location of Frogmore House, a royal retreat, and Frogmore Cottage. ...

Home Park Home Park is a football stadium in Plymouth, England. The ground has been the home of Football League One club Plymouth Argyle since 1901.Windsor, in the English county of

Berkshire Berkshire ( ; in the 17th century sometimes spelt phonetically as Barkeshire; abbreviated Berks.) is a historic county in South East England. One of the home counties, Berkshire was recognised by Queen Elizabeth II as the Royal County of Ber ...

.

Overview

The burial ground was established because the Royal Vault under St George's Chapel was becoming full; by 1928, there had been 23 interments since 1810. King

George V George V (George Frederick Ernest Albert; 3 June 1865 – 20 January 1936) was King of the United Kingdom and the British Dominions, and Emperor of India, from 6 May 1910 until his death in 1936. Born during the reign of his grandmother ...

allowed the burial ground to be made with the intention that in the future, only British sovereigns and those in the direct line of succession would be buried in the Royal Vault. Many members of the Royal Family, generally except for sovereigns and their consorts, have been interred in the Royal Burial Ground, among them

Queen Victoria Victoria (Alexandrina Victoria; 24 May 1819 – 22 January 1901) was Queen of the United Kingdom of Great Britain and Ireland from 20 June 1837 until her death in 1901. Her reign of 63 years and 216 days was longer than that of any previ ...

's children ( Princess Helena, 1846–1923;

Prince Arthur Prince Arthur may refer to: *Arthur I, Duke of Brittany (1187-1203), nephew and possible heir of Richard I of England *Arthur, Prince of Wales (1486–1502), eldest son Henry VII of England *Prince Arthur, Duke of Connaught and Strathearn Prin ...

, 1850–1942;

Princess Louise Princess Louise may refer to: ;People: * Princess Louise, Duchess of Argyll, 1848–1939, the sixth child and fourth daughter of Queen Victoria of the United Kingdom * Princess Louise, Princess Royal and Duchess of Fife, 1867–1931, the ...

, 1848–1939) and one sovereign:

Edward VIII Edward VIII (Edward Albert Christian George Andrew Patrick David; 23 June 1894 – 28 May 1972), later known as the Duke of Windsor, was King of the United Kingdom and the Dominions of the British Empire and Emperor of India from 20 January 1 ...

, 1894–1972. In the adjacent Frogmore Gardens stands the Duchess of Kent's Mausoleum built in 1861 for Queen Victoria's mother.

Burials

Buried in 1928: previously interred at St George's Chapel

Some members of the British Royal family were reburied at this cemetery in 1928, having previously been interred in the Royal Vault at St George's Chapel. * 1928 Prince Harald of Schleswig-Holstein (1876–1876), son of

Princess Helena of the United Kingdom Princess Helena (Helena Augusta Victoria; 25 May 1846 – 9 June 1923), later Princess Christian of Schleswig-Holstein, was the third daughter and fifth child of Queen Victoria and Prince Albert. Helena was educated by private tutors chose ...

. ''Interred in the Royal Vault at St George's Chapel until transferred to the Royal Burial Ground in late October 1928. His coffin is in the same grave as that of his mother.'' * 1928 Prince Francis of Teck (1870–1910), brother of Queen Mary. ''Funeral at St George's Chapel on 5 November 1910, then interred in the Royal Vault at St George's Chapel; transferred to the Royal Burial Ground in late October 1928.'' * 1928 Princess Louise Margaret, Duchess of Connaught (1860–1917), wife of Prince Arthur, Duke of Connaught. ''Cremated on the evening of 18 March 1917 at

Golders Green Crematorium Golders Green Crematorium and Mausoleum was the first crematorium to be opened in London, and one of the oldest crematoria in Britain. The land for the crematorium was purchased in 1900, costing £6,000 (the equivalent of £135,987 in 2021), ...

as first member of the Royal Family to be cremated, ashes put in an oak coffin for funeral at St George's Chapel on 19 March 1917, then placed in the Royal Vault at St George's Chapel; transferred to the Royal Burial Ground in late October 1928.'' * 1928 Prince Christian of Schleswig-Holstein (1831–1917), husband of

Princess Helena of the United Kingdom Princess Helena (Helena Augusta Victoria; 25 May 1846 – 9 June 1923), later Princess Christian of Schleswig-Holstein, was the third daughter and fifth child of Queen Victoria and Prince Albert. Helena was educated by private tutors chose ...

. ''Funeral at St George's Chapel on 1 November 1917, then interred in the Royal Vault at St George's Chapel; transferred to the Royal Burial Ground in late October 1928.'' * 1928

Lord Leopold Mountbatten Lord Leopold Arthur Louis Mountbatten (21 May 1889 – 23 April 1922) was a British Army officer and a descendant of the Hessian princely Battenberg family and the British Royal Family. A grandson of Queen Victoria, he was known as Prince Leopo ...

(1889–1922), grandson of Queen Victoria through his mother Princess Henry of Battenberg. ''Funeral at St George's Chapel on 1 May 1922, then interred in the Royal Vault at St George's Chapel; transferred to the Royal Burial Ground in late October 1928.'' * 1928

Princess Helena of the United Kingdom Princess Helena (Helena Augusta Victoria; 25 May 1846 – 9 June 1923), later Princess Christian of Schleswig-Holstein, was the third daughter and fifth child of Queen Victoria and Prince Albert. Helena was educated by private tutors chose ...

(1846–1923), daughter of Queen Victoria, wife of Prince Christian of Schleswig-Holstein. ''Funeral at St George's Chapel on 15 June 1923, then interred in the Royal Vault at St George's Chapel; transferred to the Royal Burial Ground in late October 1928.'' * 1928

Adolphus Cambridge, 1st Marquess of Cambridge Adolphus Cambridge, 1st Marquess of Cambridge, (Adolphus Charles Alexander Albert Edward George Philip Louis Ladislaus; 13 August 1868 – 24 October 1927), born Prince Adolphus of Teck and later the Duke of Teck, was a relative of the Britis ...

(1868–1927), a former Prince of Teck and brother of Queen Mary and husband of

Margaret Cambridge, Marchioness of Cambridge Margaret Evelyn Cambridge, Marchioness of Cambridge (8 April 1873 – 27 March 1929) was the sixth child and third daughter of the 1st Duke of Westminster and the wife of the 1st Marquess of Cambridge. She was known before her marriage as The L ...

. ''Funeral at St George's Chapel on 29 October 1927, then interred in the Royal Vault at St George's Chapel; transferred to the Royal Burial Ground in late October 1928. His coffin is in the same grave as that of his wife.'' * 1928 Rupert Cambridge, Viscount Trematon (1907–1928), son of

Alexander Cambridge, 1st Earl of Athlone Major General Alexander Cambridge, 1st Earl of Athlone (Alexander Augustus Frederick William Alfred George; born Prince Alexander of Teck; 14 April 1874 – 16 January 1957), was a British Army commander and major-general who served as Governo ...

. ''Funeral at St George's Chapel on 19 April 1928, then interred in the Royal Vault at St George's Chapel; transferred to the Royal Burial Ground in late October 1928.''

Burials 1929–1949

* 1929

Margaret Cambridge, Marchioness of Cambridge Margaret Evelyn Cambridge, Marchioness of Cambridge (8 April 1873 – 27 March 1929) was the sixth child and third daughter of the 1st Duke of Westminster and the wife of the 1st Marquess of Cambridge. She was known before her marriage as The L ...

(1873–1929), wife of the 1st Marquess of Cambridge. ''Funeral at St George's Chapel on 30 March 1929, then interred in the Royal Burial Ground. Her coffin is in the same grave as that of her husband.'' * 1935

Princess Victoria of the United Kingdom Princess Victoria (Victoria Alexandra Olga Mary; 6 July 1868 – 3 December 1935) was the fourth child and second daughter of King Edward VII and Queen Alexandra, and the younger sister of King George V. Early life and education Victoria ...

(1868–1935), daughter of King

Edward VII Edward VII (Albert Edward; 9 November 1841 – 6 May 1910) was King of the United Kingdom of Great Britain and Ireland and Emperor of India, from 22 January 1901 until Death and state funeral of Edward VII, his death in 1910. The second chil ...

. ''Funeral at St George's Chapel on 7 December 1935, then interred in the Royal Burial Ground on 8 January 1936.'' * 1938 Prince Arthur of Connaught (1883–1938), son of Prince Arthur, Duke of Connaught and husband of Princess Alexandra, 2nd Duchess of Fife. A former

Governor-General of South Africa The governor-general of the Union of South Africa ( af, Goewerneur-generaal van Unie van Suid-Afrika, nl, Goeverneur-generaal van de Unie van Zuid-Afrika) was the highest state official in the Union of South Africa between 31 May 1910 and 31 ...

. ''Funeral at St George's Chapel on 16 September 1938, then interred in the Royal Vault at St George's Chapel; transferred to the Royal Burial Ground on 22 September 1938.'' * 1940

Princess Louise, Duchess of Argyll Princess Louise, Duchess of Argyll, (Louisa Caroline Alberta; 18 March 1848 – 3 December 1939) was the sixth child and fourth daughter of Queen Victoria and Prince Albert. In her public life, she was a strong proponent of the arts and highe ...

(1848–1939), daughter of Queen Victoria, wife of the 9th Duke of Argyll. ''Cremated at

Golders Green Crematorium Golders Green Crematorium and Mausoleum was the first crematorium to be opened in London, and one of the oldest crematoria in Britain. The land for the crematorium was purchased in 1900, costing £6,000 (the equivalent of £135,987 in 2021), ...

, ashes put in an oak coffin for funeral at St George's Chapel on 12 December 1939, then placed in the Royal Vault at St George's Chapel; transferred to the Royal Burial Ground on 13 March 1940.'' * 1942

Prince Arthur, Duke of Connaught and Strathearn Prince Arthur, Duke of Connaught and Strathearn (Arthur William Patrick Albert; 1 May 185016 January 1942), was the seventh child and third son of Queen Victoria of the United Kingdom and Prince Albert of Saxe-Coburg and Gotha. He served as G ...

(1850–1942), son of Queen Victoria. A former

Governor General of Canada The governor general of Canada (french: gouverneure générale du Canada) is the federal viceregal representative of the . The is head of state of Canada and the 14 other Commonwealth realms, but resides in oldest and most populous realm ...

. ''Funeral at St George's Chapel on 23 January 1942, then interred in the Royal Vault at St George's Chapel; transferred to the Royal Burial Ground on 18 March 1942.'' * 1948 Princess Helena Victoria of Schleswig-Holstein (1870–1948), daughter of

Princess Helena of the United Kingdom Princess Helena (Helena Augusta Victoria; 25 May 1846 – 9 June 1923), later Princess Christian of Schleswig-Holstein, was the third daughter and fifth child of Queen Victoria and Prince Albert. Helena was educated by private tutors chose ...

. ''Funeral at St George's Chapel on 17 March 1948, then interred in the Royal Burial Ground.''

Burials 1950–1979

* 1956 Princess Marie Louise of Schleswig-Holstein (1872–1956), daughter of Prince Christian of Schleswig-Holstein and

Princess Helena of the United Kingdom Princess Helena (Helena Augusta Victoria; 25 May 1846 – 9 June 1923), later Princess Christian of Schleswig-Holstein, was the third daughter and fifth child of Queen Victoria and Prince Albert. Helena was educated by private tutors chose ...

and also granddaughter of

Queen Victoria Victoria (Alexandrina Victoria; 24 May 1819 – 22 January 1901) was Queen of the United Kingdom of Great Britain and Ireland from 20 June 1837 until her death in 1901. Her reign of 63 years and 216 days was longer than that of any previ ...

. ''Funeral at St George's Chapel on 14 December 1956, then interred in the Royal Burial Ground.'' * 1957 The Earl of Athlone (1874–1957), brother of Queen Mary and husband of

Princess Alice, Countess of Athlone Princess Alice, Countess of Athlone (Alice Mary Victoria Augusta Pauline; 25 February 1883 – 3 January 1981) was a member of the British royal family. She is the longest-lived British princess of royal blood, and was the last surviving grand ...

. A former Prince of Teck, a former

Governor-General of South Africa The governor-general of the Union of South Africa ( af, Goewerneur-generaal van Unie van Suid-Afrika, nl, Goeverneur-generaal van de Unie van Zuid-Afrika) was the highest state official in the Union of South Africa between 31 May 1910 and 31 ...

and a former

Governor General of Canada The governor general of Canada (french: gouverneure générale du Canada) is the federal viceregal representative of the . The is head of state of Canada and the 14 other Commonwealth realms, but resides in oldest and most populous realm ...

. ''Funeral at St George's Chapel on 19 January 1957, then interred in the Royal Burial Ground. His coffin is in the same grave as that of his wife.'' * 1968

Prince George, Duke of Kent Prince George, Duke of Kent, (George Edward Alexander Edmund; 20 December 1902 – 25 August 1942) was a member of the British royal family, the fourth son of King George V and Queen Mary. He was a younger brother of kings Edward VIII and Geo ...

(1902–1942), son of King

George V George V (George Frederick Ernest Albert; 3 June 1865 – 20 January 1936) was King of the United Kingdom and the British Dominions, and Emperor of India, from 6 May 1910 until his death in 1936. Born during the reign of his grandmother ...

, husband of

Princess Marina, Duchess of Kent Princess Marina, Duchess of Kent (27 August 1968), born Princess Marina of Greece and Denmark ( el, Μαρίνα), was a Greek princess by birth and a British princess by marriage. She was a daughter of Prince Nicholas of Greece and Denmark a ...

. ''Funeral at St George's Chapel on 29 August 1942, then interred in the Royal Vault at St George's Chapel; transferred to the Royal Burial Ground on 29 August 1968, the day before his wife's funeral.'' * 1968

Princess Marina, Duchess of Kent Princess Marina, Duchess of Kent (27 August 1968), born Princess Marina of Greece and Denmark ( el, Μαρίνα), was a Greek princess by birth and a British princess by marriage. She was a daughter of Prince Nicholas of Greece and Denmark a ...

(1906–1968), wife of

Prince George, Duke of Kent Prince George, Duke of Kent, (George Edward Alexander Edmund; 20 December 1902 – 25 August 1942) was a member of the British royal family, the fourth son of King George V and Queen Mary. He was a younger brother of kings Edward VIII and Geo ...

. ''Interred in the Royal Burial Ground on 30 August 1968.'' * 1972

Prince Edward, Duke of Windsor Edward VIII (Edward Albert Christian George Andrew Patrick David; 23 June 1894 – 28 May 1972), later known as the Duke of Windsor, was King of the United Kingdom and the Dominions of the British Empire and Emperor of India from 20 January 19 ...

(1894–1972), eldest son of King

George V George V (George Frederick Ernest Albert; 3 June 1865 – 20 January 1936) was King of the United Kingdom and the British Dominions, and Emperor of India, from 6 May 1910 until his death in 1936. Born during the reign of his grandmother ...

and formerly King

Edward VIII Edward VIII (Edward Albert Christian George Andrew Patrick David; 23 June 1894 – 28 May 1972), later known as the Duke of Windsor, was King of the United Kingdom and the Dominions of the British Empire and Emperor of India from 20 January 1 ...

. ''Funeral at St George's Chapel on 5 June 1972, then interred in the Royal Burial Ground.'' * 1972

Prince William of Gloucester Prince William of Gloucester (William Henry Andrew Frederick; 18 December 1941 – 28 August 1972) was a grandson of King George V and paternal cousin of Queen Elizabeth II. At birth he was fourth in line to the throne; he was ninth in lin ...

(1941–1972), son of Prince Henry, Duke of Gloucester. ''Interred in the Royal Burial Ground on 2 September 1972.'' * 1972 Sir Alexander Ramsay (1881–1972), husband of

Princess Patricia of Connaught Lady Victoria Patricia Helena Elizabeth Ramsay, (born Princess Patricia of Connaught; 17 March 1886 – 12 January 1974) was a granddaughter of Queen Victoria. Upon her marriage to Alexander Ramsay, she relinquished her title of a British pri ...

and former

Fifth Sea Lord The Fifth Sea Lord was formerly one of the Naval Lords and members of the Board of Admiralty that controlled the Royal Navy. The post's incumbent had responsibility for naval aviation. History In 1805, for the first time, specific functions we ...

. ''Interred in the Royal Burial Ground in October 1972.'' * 1974

Princess Patricia of Connaught Lady Victoria Patricia Helena Elizabeth Ramsay, (born Princess Patricia of Connaught; 17 March 1886 – 12 January 1974) was a granddaughter of Queen Victoria. Upon her marriage to Alexander Ramsay, she relinquished her title of a British pri ...

(1886–1974), daughter of Prince Arthur, Duke of Connaught, and wife of Sir Alexander Ramsay. ''Interred in the Royal Burial Ground in January 1974.'' * 1974 Prince Henry, Duke of Gloucester (1900–1974), son of King

George V George V (George Frederick Ernest Albert; 3 June 1865 – 20 January 1936) was King of the United Kingdom and the British Dominions, and Emperor of India, from 6 May 1910 until his death in 1936. Born during the reign of his grandmother ...

, husband of

Princess Alice, Duchess of Gloucester Princess Alice, Duchess of Gloucester, (born Lady Alice Christabel Montagu Douglas Scott; 25 December 1901 – 29 October 2004) was the wife of Prince Henry, Duke of Gloucester, the third son of King George V and Queen Mary. She was the moth ...

. A former

Governor-General of Australia The governor-general of Australia is the representative of the monarch, currently King Charles III, in Australia.Patrick Plunket, 7th Baron Plunket Patrick Terence William Span Plunket, 7th Baron Plunket, (8 September 1923 – 28 May 1975), was Equerry to Queen Elizabeth II and Deputy Master of the Household of the Royal Household (1954–1975). Lord Plunket was born into an old Anglo-Iri ...

(1923–1975), Courtier, equerry to King

George VI George VI (Albert Frederick Arthur George; 14 December 1895 – 6 February 1952) was King of the United Kingdom and the Dominions of the British Commonwealth from 11 December 1936 until his death in 1952. He was also the last Emperor of I ...

and Queen

Elizabeth II Elizabeth II (Elizabeth Alexandra Mary; 21 April 1926 – 8 September 2022) was Queen of the United Kingdom and other Commonwealth realms from 6 February 1952 until her death in 2022. She was queen regnant of 32 sovereign states durin ...

. ''Interred in the Royal Burial Ground in June 1975.''

Burials 1980–present

* 1981

Princess Alice, Countess of Athlone Princess Alice, Countess of Athlone (Alice Mary Victoria Augusta Pauline; 25 February 1883 – 3 January 1981) was a member of the British royal family. She is the longest-lived British princess of royal blood, and was the last surviving grand ...

(1883–1981), last surviving grandchild of

Queen Victoria Victoria (Alexandrina Victoria; 24 May 1819 – 22 January 1901) was Queen of the United Kingdom of Great Britain and Ireland from 20 June 1837 until her death in 1901. Her reign of 63 years and 216 days was longer than that of any previ ...

, wife of

Alexander Cambridge, 1st Earl of Athlone Major General Alexander Cambridge, 1st Earl of Athlone (Alexander Augustus Frederick William Alfred George; born Prince Alexander of Teck; 14 April 1874 – 16 January 1957), was a British Army commander and major-general who served as Governo ...

. ''Funeral at St George's Chapel on 8 January 1981, then interred in the Royal Burial Ground. Her coffin is in the same grave as that of her husband.'' * 1981

George Cambridge, 2nd Marquess of Cambridge George Francis Hugh Cambridge, 2nd Marquess of Cambridge, (11 October 1895 – 16 April 1981), known as Prince George of Teck until 1917 and as Earl of Eltham from 1917 to 1927, was a relative of the British royal family, a great-great-grand ...

(1895–1981), son of the 1st Marquess of Cambridge. ''Interred in the Royal Burial Ground on 23 April 1981. His coffin is in the same grave as that of his wife.'' * 1986

Wallis, Duchess of Windsor Wallis, Duchess of Windsor (born Bessie Wallis Warfield, later Simpson; June 19, 1896 – April 24, 1986), was an American socialite and wife of the former King Edward VIII. Their intention to marry and her status as a divorcée caused a ...

(1896–1986), wife of

Prince Edward, Duke of Windsor Edward VIII (Edward Albert Christian George Andrew Patrick David; 23 June 1894 – 28 May 1972), later known as the Duke of Windsor, was King of the United Kingdom and the Dominions of the British Empire and Emperor of India from 20 January 19 ...

. ''Funeral at St George's Chapel on 29 April 1986, then interred in the Royal Burial Ground, next to the grave of her husband.'' * 1988 Dorothy Cambridge, Marchioness of Cambridge (1899–1988), wife of The 2nd Marquess of Cambridge. ''Interred in the Royal Burial Ground in April 1988. Her coffin is in the same grave as that of her husband.'' * 1994 Lady May Abel Smith (1906–1994), daughter of

Alexander Cambridge, 1st Earl of Athlone Major General Alexander Cambridge, 1st Earl of Athlone (Alexander Augustus Frederick William Alfred George; born Prince Alexander of Teck; 14 April 1874 – 16 January 1957), was a British Army commander and major-general who served as Governo ...

, and wife of Sir Henry Abel Smith. ''Interred in the Royal Burial Ground on 9 June 1994; her husband's ashes were buried there at the same time. Both are buried in the same grave.'' * 1994 Sir Henry Abel Smith (1900–1993), husband of Lady May Abel Smith and former

Governor of Queensland The governor of Queensland is the representative in the state of Queensland of the monarch of Australia. In an analogous way to the governor-general of Australia at the national level, the governor performs constitutional and ceremonial func ...

. ''Cremated, ashes interred in the Royal Burial Ground at the time of his wife's funeral there on 9 June 1994. Both are buried in the same grave.'' * 2004

Princess Alice, Duchess of Gloucester Princess Alice, Duchess of Gloucester, (born Lady Alice Christabel Montagu Douglas Scott; 25 December 1901 – 29 October 2004) was the wife of Prince Henry, Duke of Gloucester, the third son of King George V and Queen Mary. She was the moth ...

(1901–2004), wife of Prince Henry, 1st Duke of Gloucester. ''Funeral at St George's Chapel on 5 November 2004, then interred in the Royal Burial Ground.'' * 2005 Sir Angus Ogilvy (1928–2004), husband of Princess Alexandra of Kent. ''Funeral at St George's Chapel on 5 January 2005, then interred in the Royal Burial Ground.''

Formerly buried at the Royal Burial Ground

* Queen Maria, Queen Mother of Yugoslavia (1900–1961), great-granddaughter of Queen Victoria, wife of King Alexander I of Yugoslavia. ''Died in London, funeral on 2 July 1961, then interred in the Royal Burial Ground. Remains were exhumed on 26 April 2013 and transferred to

Oplenac The St. George's Church in Oplenac ( sr-cyrl, Црква Светог Ђорђа на Опленцу, Crkva Svetog Đorđa na Oplencu), also known as Oplenac (Опленац), is the mausoleum of the Serbian and Yugoslav royal house of Karađorđ ...

, Serbia, on 28 April.''

Public access

Frogmore House Frogmore House is a 17th-century English country house owned by the Crown Estate. It is a historic Grade I listed building. The house is located on the Frogmore estate, which is situated within the grounds of the Home Park in Windsor, Berks ...

and its gardens are usually open to the public on about six days each year, usually around

Easter Easter,Traditional names for the feast in English are "Easter Day", as in the '' Book of Common Prayer''; "Easter Sunday", used by James Ussher''The Whole Works of the Most Rev. James Ussher, Volume 4'') and Samuel Pepys''The Diary of Samue ...

and the August Bank Holiday. The Royal Burial Ground may be viewed from around its perimeter on the days on which the gardens are open to the public. The Duchess of Kent's Mausoleum may also be viewed externally, but is never open to the public. The Royal Mausoleum, the resting place of Queen Victoria and her husband Prince Albert, is structurally unsound and has been closed to the public since 2007. It was reported in August 2011 that repairs might not be completed for a further ten years. The Royal Mausoleum used to open on the Wednesday nearest Queen Victoria's birthday, 24 May, and occasionally on other days when the grounds were open. Restoration of the mausoleum began in June 2018, with the aims to create a dry moat around it and to replace the roof to protect it from the long-standing problem of water infiltration.

References

External links

Frogmore Royal Burial Ground
(near bottom of page) {{Cemeteries in England, state=collapsed 1928 establishments in England Cemeteries in Berkshire Tourist attractions in Berkshire Burial sites of British royal houses Burial sites of the House of Schleswig-Holstein-Sonderburg-Augustenburg Frogmore