HMNB Devonport in the context of "His Majesty's Naval Service"

His Majesty's Naval Base, Portsmouth (HMNB Portsmouth) is one of three operating bases in the United Kingdom for the Royal Navy (the others being HMNB Clyde and HMNB Devonport). Portsmouth Naval Base is part of the city of Portsmouth; it is located on the eastern shore of Portsmouth Harbour, north of the Solent and the Isle of Wight. For centuries it was officially known as HM Dockyard, Portsmouth: as a Royal Navy Dockyard, Portsmouth functioned primarily as a state-owned facility for building, repairing and maintaining warships; for a time it was the largest industrial site in the world.

From the 1970s, the term 'Naval Base' began to be used for Portsmouth (and other Royal Dockyards), acknowledging a greater focus on personnel and support elements alongside the traditional industrial emphases. In 1984 Portsmouth's Royal Dockyard function was significantly downsized and downgraded, and was formally renamed the 'Fleet Maintenance and Repair Organisation' (FMRO). The FMRO was privatised in 1998; in 2002, shipbuilding (which had not taken place on site since the late 1960s) resumed in the form of block construction, but this again ceased in 2014.

HMS Ocean was a Landing Platform Helicopter, formerly the UK's helicopter carrier and the fleet flagship of the Royal Navy. She was designed to support amphibious landing operations and to support the staff of Commander UK Amphibious Force and Commander UK Landing Force. She was constructed in the mid-1990s by Kvaerner Govan on the River Clyde and fitted out by VSEL at Barrow-in-Furness prior to trials and subsequent acceptance in service. Ocean was commissioned in September 1998 at her home port HMNB Devonport, Plymouth.

In December 2017, the Brazilian Navy confirmed the purchase of the ship for £84.6 million. Following her decommissioning from Royal Navy service on 27 March 2018, she arrived in Rio de Janeiro on 25 August 2018, rechristened as the Atlântico and now serves as the flagship of the Brazilian Navy.

His Majesty's Naval Base, Clyde (HMNB Clyde; also HMS Neptune), primarily sited at Faslane on the Gare Loch, is one of three operating bases in the United Kingdom for the Royal Navy (the others being HMNB Devonport and HMNB Portsmouth). It is the navy's headquarters in Scotland and is best known as the home of Britain's nuclear weapons, in the form of nuclear submarines armed with Trident missiles.

Serco Marine Services is a Private Finance Initiative contract, with Serco Group, to deliver auxiliary services to His Majesty's Naval Service (incl. Royal Navy, Royal Marines and Royal Fleet Auxiliary).

Marine Services primarily operates from the nation's three main naval bases, HMNB Portsmouth, HMNB Devonport and HMNB Clyde, but also supports training and operations overseas, as well as at various British Overseas Territories.