HMS Excellent itself forms part of the Maritime Warfare School, with a Headquarters at HMS Collingwood, although a number of lodger units are resident within the site, the principal of which is the Headquarters of Commander in Chief Fleet.
MWS elements within the site are:
HMS Excellent also provides administrative and infrastructure support to the Maritime Warfare School elements at Defence Diving School, Horsea Island and small arms ranges at Tipner.
Lodger units are:
Whale Island is predominantly reclaimed land, using the deposits dredged from Portsmouth harbour during the Victorian era, increasing the land area by around 125%. It has served as a training facility since that time, predominantly in gunnery and the associated discipline of Parade Training leading to the situation where Gunnery Instructors (GIs) were responsible for Parade Training throughout the fleet. This situation persists with the successors to the Gunnery branch, the Above Water Weapons branch, retaining the responsibility for Parade Training and generally retaining the form of address, GI.
The establishment was recommissioned in 1994 following the closure of the old HMS Phoenix, school of Fire Fighting and Damage Control, in nearby Tipner and Horsea Island. It also served as home for the recently closed RN School of Leadership and Management which had moved from HMS Royal Arthur near Corsham in Wiltshire.
The Portsmouth Field Gun Crew, competing in the Royal Navy field gun competition at the Royal Tournament, was based at the site. CINCFLEET staff have subsequently competed in the Brickwoods field gun competition at HMS Collingwood.
Participation in events at Whitehall and elsewhere is known as November Ceremonies within the Naval Service.
Personnel are drawn from volunteers throughout the service.