In British naval usage, the term 'port admiral' had two distinct meanings, one generic, one specific.
Generic use
Historically, 'port admiral' was used as a generic term for the senior naval officer having authority over all commissioned ships and naval personnel stationed at a particular home base or anchorage. By this definition, the port admiral did not have oversight of the localRoyal Navy Dockyard ; Dockyards were overseen by an independent official: usually a resident Commissioner appointed by the Navy Board or an Admiral-superintendent appointed by the Admiralty. The distinction is seen in informal correspondence such as the following, dated 1837: "The Devonport regatta... was attended by the Port-Admiral, the Admiral-Superintendent of the Dockyard... and other persons of consideration." In practice the offices of port admiral and admiral-superintendent were sometimes combined.
Specific use
In 1971 the remaining Admirals-Superintendent of HM Dockyards were redesignated as Port Admirals; unlike the above use of the term, this was an official designation. This reflected a consolidation of previously distinct command roles, and coincided with the appointment of civilian Dockyard General Managers to oversee work within the Dockyards across all departments.
Current use
Today, both uses of the term are obsolete as the equivalent appointments are not of flag-officer rank.
The rank of port admiral appears in several futuristic military organisations in science fiction. In the Lensman novels, the rank of port admiral appeared as the most senior naval officer of the Galactic Patrol, with de facto supreme command over its forces. Three specific port admirals were mentioned by name: Roderick K. Kinnison, the first port admiral and ancestor of series protagonist Kimball Kinnison; Port Admiral Haynes, who commanded the patrol during Kimball Kinnison's early career and was a mentor and father figure to him; and Raoul Laforge, an academy classmate and friend of Kinnison's who had replaced the retired Haynes by the time of the last novel. In the Starfire universe, a fleet admiral holds the position of port admiral, presiding over The Yard, the Terran Federation's largest and most important naval base and shipyard.
