The Admiralty Yard Craft Service was the civilian service which operated auxiliary vessels for the BritishAdmiralty, mainly in HM Dockyards or the vicinity. It was renamed the Port Auxiliary Service (PAS) between 1960 and 1962, and later the Royal Maritime Auxiliary Service after 1970.The service operated tugs, harbour ferries, launches, and lighters. Although some of its tugs were classified as ocean-going, it did not operate ocean-going supply vessels, which were the responsibility of the Royal Fleet Auxiliary. The Yard Craft Service crews answered to the Captain's Department in each dockyard.
See more at Wikipedia.org...