In 1939, candidates were advertised for to complete the strength of the Royal Marine Police Special Reserve which was a Force of Special Constables on a civil basis to supplement the Royal Marine Police in time of war or emergency. Applicants were to be between 45 and 55 years old and physically fit. By 1941, additional advertisements were made to supplement the Royal Marine Police for the purpose of policing and providing fire brigades for Naval Dockyards and establisments during the War. Applicants were to be between the ages of 30 and 42.

The rates of pay and allowances on being called up were a basic rate of 51s. 11d. per week with a lodging allowance, payable to married men who could perform their duties from their homes and other men for whom Government accommodation was not provided of 10s. 6d. per week. A Special Subsistence Allowance, payable to married men who could not perform their duties from their homes, was paid at 14s. per week. A free kit was issued on joining and a Kit Upkeep Allowance was paid for its maintenance.

On 2 October 1949, the Admiralty Constabulary came into being. The merger had been under consideration for several years. It was the new name for the Admiralty Police Force and into it were merged the Royal Marine Police, Royal Marine Police Special Reserve and the Admiralty Civil Police.