During the Second World War the Military Police grew from 4,121 all ranks to over 50,000 all ranks within six major branches of specialists: Special Investigation Branch – formed in 1940, with 19 detectives from the Metropolitan Police transferred to the Army for deployment in France. From this small beginning the Branch expanded into numerous Sections which were deployed both in the UK and overseas, providing the Corps with its own Criminal Investigation Department to conduct more detailed and protracted investigations into organised crime and serious offences such as murder. Provost Wing – responsible for general policing. Provost Companies were included in the order of battle of Home Commands, Armoured, Infantry and Airborne Divisions, as well as at Army and Corps level and with independent Brigades. From 1942, "Ports Provost" Companies were raised, consisting of a mix of Provost and Vulnerable Points Sections, which were deployed on security and policing duties within ports and docks. Vulnerable Points Wing – formed in 1941 to provide security of static locations and establishments. They were known as "blue caps" from the Oxford blue cloth covers worn on their service dress caps. Originally intended to act as static Companies and detachments, VP Coys were later deployed in North West Europe, guarding prisoner of war camps and other static installations. The VP Wing was quickly phased out at the end of the war, but re-appeared briefly in the Supplementary Reserve/Army Emergency Reserve between 1950 and 1961. Traffic Control Wing – formed in 1941, TC Coys were deployed throughout the United Kingdom, releasing Provost Companies from the tasks of traffic control. TC Coys were later deployed in the Middle East, Italy and North-West Europe. The Wing was phased out of the Corps by 1946. (Many sources over the years continue to erroneously state that personnel of the Traffic Control Wing wore white cloth cap covers. This is not the case. CMP (TC) personnel did not wear cap covers when on duty, unless they had undergone a basic course in police duties, in which case they were authorised to wear red top covers as per the Provost Wing). Field Security Wing – formed in 1937. Personnel wore Lincoln green cap covers, green brassards and brass shoulder titles on their tunics with the letters "FSP", to distinguish them from the rest of the Corps. They wore the standard CMP cap badge, but unofficially ground down the wording "MILITARY