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 During the 1860s, the flintlock pistols that had been purchased in 1829 were decommissioned from service, being superseded by 622 Beaumont–Adams revolvers firing the .450 cartridge which were loaned from the army stores at the Tower of London following the Clerkenwell bombing.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
Metropolitan Police Service being fitted with Battenburg. The National Police Air Service has a base at Lippitts Hill, in Essex, which houses three helicopters to support surrounding forces, including the Met. A marine policing unit operates 22 vessels from its base in Wapping. Annual expenditure for single years, selected by quarter centuries. In 2011/12, £2,754m was spent on staff wages. Crimes reported within the Metropolitan Police District, selected by quarter centuries. The following table shows the percentage detection rates for the Metropolitan Police by offence group for 2010/11. The Metropolitan Police Service “screened out” 34,164 crimes the day they were reported in 2017