History of the Metropolitan Police Service by the end of the 19th century. During the 1860s, the flintlock pistols that had been purchased in 1829 were decommissioned from service, being superseded by 622 Beaumont–Adams revolvers firing the .450 cartridge which were loaned from the army stores at the Tower of London following the Clerkenwell bombing. In 1883, a ballot was carried out to gather information on officers' views on whether they wished to be armed, and 4,430 out of 6,325 officers serving on outer divisions requested to be issued with revolvers. The now obsolete Adams revolver was returned to stores for emergencies, and the Bulldog 'Metropolitan
History of the Metropolitan Police Service often called for assistance from the Metropolitan Police because of their detective experience. The last case of this was when the now defunct Buckinghamshire Constabulary called upon the MPS to help in the investigation of the Great Train Robbery. In 1931, Hugh Trenchard was appointed as Police Commissioner Trenchard served as head of the Metropolitan Police until 1935 and during his tenure he instigated several changes. These included limiting membership of the Police Federation, introducing limited terms of employment and the short-lived creation of separate career paths for the lower and higher ranks akin to the military system of officer