From completion to early 1970 Sir Tristram was managed by British India Steam Navigation Company. In January 1972 Sir Tristram was part of an anti-invasion task force off British Honduras, together with, and . In 1977 Sir Tristram was used as a guest ship for the Queens Silver Jubilee Fleet Review at Spithead in the Solent.[3]
In April 1982 Sir Tristram was diverted from Belize to the Falkland Islands to take part in Operation Corporate, the British effort to retake the Falkland Islands.
On 8 June, while transporting men and equipment to Fitzroy Cove alongside the, Sir Tristram was attacked by Douglas A-4 Skyhawks of the Argentine Air Force's V Brigada Aérea (FAA), each loaded with three Mark 82 bombs.[4] At approximately 14:00 local time the decks were strafed and two crew were killed. A 500 lb bomb penetrated the deck, but failed to explode immediately, allowing the remaining crew to be evacuated. Following the later explosion, Sir Tristram was abandoned. Immediately following the end of the conflict, Sir Tristram was towed to Port Stanley, where she was used as an accommodation ship.[5] [6] Sir Tristram then returned to the United Kingdom in 1983 on a heavy lift ship and was extensively rebuilt.[5]
Following the rebuild, Sir Tristram re-entered active service in 1985, and saw service in the Gulf War, and the Balkan conflicts of the 1990s. The ship supported relief operations for Hurricane Mitch off Central America. In 2000 the ship was deployed to Sierra Leone in support of British operations there, followed by a cruise to the Baltic Sea in support of mine countermeasure vessels. In early 2001 Sir Tristram returned to Sierra Leone to take over from as the ship supporting British forces ashore there. In 2003 the ship was deployed as part of the largest British fleet for 20 years in support of the invasion of Iraq.
The ship was decommissioned on 17 December 2005 but continues to be used for training purposes by the Special Boat Service and other elements of the UK Special Forces group. She is now based at Portland Harbour.[7]