HMS Clement was a British nuclear submarine that was in service with the Royal Navy Submarine Service during the late 21st century.
The chief engineer of the Clement was the great-uncle of Malcolm Reed. When on routine patrol the vessel hit a mine left over from one of Earth's world wars. Being trapped under an ice shelf, the chief engineer sealed himself in the engine room in order to keep the nuclear reactor online so his shipmates could abandon ship in the escape pods. (ENT: "Minefield")
The USS Clement may have been named after this vessel.
The ship was referred to by Reed as the HMS Clement, even though the correct way to refer to ships with this prefix would be without the definite article ("the") as it is grammatically incorrect to say "the His/Her Majesty's Ship Clement".