Harry William Fensom (4 February 1921 – 1 November 2010) was an English electronic engineer with the

GPO GPO may refer to: Government and politics * General Post Office, Dublin * General Post Office, in Britain * Social Security Government Pension Offset, a provision reducing benefits * Government Pharmaceutical Organization, a Thai state enterpris ...

. During

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

he worked with

Tommy Flowers Thomas Harold Flowers MBE (22 December 1905 – 28 October 1998) was an English engineer with the British General Post Office. During World War II, Flowers designed and built Colossus, the world's first programmable electronic computer, to help ...

Bletchley Park Bletchley Park is an English country house and estate in Bletchley, Milton Keynes ( Buckinghamshire) that became the principal centre of Allied code-breaking during the Second World War. The mansion was constructed during the years following ...

Colossus Colossus, Colossos, or the plural Colossi or Colossuses, may refer to: Statues * Any exceptionally large statue ** List of tallest statues ** :Colossal statues * ''Colossus of Barletta'', a bronze statue of an unidentified Roman emperor * ''Col ...

, the world's first electronic computer, that helped to decode encrypted German messages using the

Lorenz cipher The Lorenz SZ40, SZ42a and SZ42b were German rotor stream cipher machines used by the German Army during World War II. They were developed by C. Lorenz AG in Berlin. The model name ''SZ'' was derived from ''Schlüssel-Zusatz'', meaning ''cipher ...

. After the war, he worked on

ERNIE Ernie is a masculine given name, frequently a short form (hypocorism) of Ernest, Ernald, Ernesto, or Verner. It may refer to: People * Ernie Accorsi (born 1941), American football executive * Ernie Adams (disambiguation) * Ernie Afaganis (born c ...

, a machine based on Colossus engineering that was used to generate bond numbers for the Premium Bond draw.

Early life and education

Fensom was born in

Catford Catford is a district in south east London, England, and the administrative centre of the London Borough of Lewisham. It is southwest of Lewisham itself, mostly in the Rushey Green (ward), Rushey Green and Catford South Ward (electoral subdiv ...

, in South London. Shortly after his birth the family moved to

Fife Fife (, ; gd, Fìobha, ; sco, Fife) is a council area, historic county, registration county and lieutenancy area of Scotland. It is situated between the Firth of Tay and the Firth of Forth, with inland boundaries with Perth and Kinross (i ...

, where they stayed until 1928. His secondary education was at the

Royal Liberty School The Royal Liberty School is a secondary school for boys aged 11 to 16, located in Gidea Park in the London Borough of Havering, England. The school is situated on Upper Brentwood Road about 400 metres north of Gidea Park railway station, and a ...

in Gidea Park where he excelled in mathematics and the sciences. He left school at 16, shunning a university education in favour of finding work. Whilst working for the GPO as an engineer, Fensom continued his education at night school, studying for

City and Guilds The City and Guilds of London Institute is an educational organisation in the United Kingdom. Founded on 11 November 1878 by the City of London and 16 livery companies – to develop a national system of technical education, the institute has ...

at East Ham,

Borough A borough is an administrative division in various English-speaking countries. In principle, the term ''borough'' designates a self-governing walled town, although in practice, official use of the term varies widely. History In the Middle Ag ...

and

Northampton Northampton () is a market town and civil parish in the East Midlands of England, on the River Nene, north-west of London and south-east of Birmingham. The county town of Northamptonshire, Northampton is one of the largest towns in England; ...

polytechnics.

World War II

In 1942, Fensom was sent to work at Dollis Hill Research Station with

, Sidney Broadhurst and William Chandler. He began working on projects connected to the

Enigma Enigma may refer to: *Riddle, someone or something that is mysterious or puzzling Biology *ENIGMA, a class of gene in the LIM domain Computing and technology *Enigma (company), a New York-based data-technology startup * Enigma machine, a family o ...

machine. These included the Shark and the Cobra, which was the first electronic codebreaking device. Other projects included the Nightingale, used to decode messages from the Hagelin

C-36 C36 or C-36 may refer to: Vehicles ;Aircraft * Caspar C 36, a German reconnaissance aircraft * Castel C-36, a French glider * EKW C-36, a Swiss multi-purpose combat aircraft * Lockheed C-36 Electra, an American military transport aircraft ;Au ...

which was being used by the Italians, the Tunny and the

Heath Robinson William Heath Robinson (31 May 1872 – 13 September 1944) was an English cartoonist, illustrator and artist, best known for drawings of whimsically elaborate machines to achieve simple objectives. In the UK, the term "Heath Robinson contr ...

. Fensom's work took him increasingly to

and in December 1943 the first

machine was installed at Bletchley Park to decode the messages from the

Lorenz Lorenz is an originally German name derived from the Roman surname Laurentius, which means "from Laurentum". Given name People with the given name Lorenz include: * Prince Lorenz of Belgium (born 1955), member of the Belgian royal family by h ...

machine. The Mark II Colossus was installed on 1 June 1944 in time for the

D-day landings The Normandy landings were the landing operations and associated airborne operations on Tuesday, 6 June 1944 of the Allied invasion of Normandy in Operation Overlord during World War II. Codenamed Operation Neptune and often referred to as D ...

on 6 June. By the end of the war there were ten functioning Colossi working around the clock helping to decipher the messages of German High Command. The deciphered messages provided the Allies with crucial intelligence on what enemy armed forces were plotting. The allies knew for example that Hitler had swallowed the bait that the D-Day landings in June 1944 would be at Calais rather than Normandy. This gave the Allies a decisive advantage. Sir

Harry Hinsley Sir Francis Harry Hinsley, (26 November 1918 – 16 February 1998) was an English historian and cryptanalyst. He worked at Bletchley Park during the Second World War and wrote widely on the history of international relations and British Int ...

, as the official historian, in his book 'British Intelligence in the Second World War' gave his opinion that the breaking of the Enigma and Lorenz codes shortened the war by at least two years and saved hundreds of thousands of lives.

Post war activity

After the war, Fensom continued to work for the GPO at Dollis Hill. In 1957 he was given charge by Sydney Broadhurst of the system design of a machine called

, which was to be used to deliver the winning numbers of the prizes for the Premium Bonds. After his retirement, Fensom assisted

Tony Sale Tony may refer to: People and fictional characters * Tony (given name), including a list of people and fictional characters * Gregory Tony (born 1978), American law enforcement officer * Motu Tony (born 1981), New Zealand international rugby leag ...

in the Colossus rebuild project at the

National Museum of Computing The National Museum of Computing is a museum in the United Kingdom dedicated to collecting and restoring History of computing hardware, historic computer systems. The museum is based in rented premises at Bletchley Park in Milton Keynes, Bucki ...

References

{{DEFAULTSORT:Fensom, Harry English electrical engineers Bletchley Park people People from Catford 1921 births 2010 deaths