The Class Z Reserve was a Reserve contingent of the

British Army The British Army is the principal land warfare force of the United Kingdom, a part of the British Armed Forces along with the Royal Navy and the Royal Air Force. , the British Army comprises 79,380 regular full-time personnel, 4,090 Gurk ...

consisting of previously enlisted soldiers, now discharged. The first Z Reserve was authorised by an Army Order of 3 December 1918. When expected problems with violations of the

Armistice with Germany The Armistice of 11 November 1918 was the armistice signed at Le Francport near Compiègne that ended fighting on land, sea, and air in World War I between the Entente and their last remaining opponent, Germany. Previous armistices ...

did not eventuate, the Z Reserve was abolished on 31 March 1920. Following the Second World War, a new Z Reserve of soldiers and officers who had served between 3 September 1939 and 31 December 1948 were available for recall if under 45 years of age.The Bulletin – Google Books
/ref>

References

Military units and formations of the British Army History of the British Army {{UK-mil-unit-stub