The Royal Naval Auxiliary Service (RNXS) was a uniformed, unarmed, civilian volunteer service, administered and trained by the Royal Navy to operate in the ports and anchorages of the United Kingdom in an emergency. Although the abbreviated title would logically have been RNAS this abbreviation had long been taken by the various Royal Naval Air Stations, so RNXS it was. It maintained training units, and vessels at most major ports in the UK. and was formed in 1963 from the amalgamation of the Royal Naval Mine-watching Service (RNMWS) and Admiralty Ferry Crew Association in response to the perceived nuclear threat to British ports. The service was disbanded on 31 March 1994 due to Ministry of Defence (MOD) cuts. Most vessels from its fleet were transferred to the Royal Navy or sold, with the exception of XSV Loyal Volunteer, which was struck by a ro-ro ferry while berthed in Ipswich Harbour and was later scrapped.

The Archer class is a class of patrol and training vessel in service with the United Kingdom's Royal Navy, commonly referred to as a "fast training boat". Most are assigned to Coastal Forces Squadron. HMS Tracker and HMS Raider are armed and provide maritime force protection to high value shipping in the Firth of Clyde and are most commonly employed as escorts for submarines transiting to Faslane. Pursuer and Dasher were also armed during their deployment on maritime force protection duties with the Gibraltar Squadron from 2020-2022.