The Oberon, that featured in one of the Early Dad's Army episodes.
My wife's grandfather had an interesting career, enlisted in the Army before ending his engagement the day after the Battle of Loos. A short time later he joined the Royal Naval Patrol Service and served until mid 1919. He rejoined the RNPS in 1939 for the duration. Characteristically he said little and what the family thought they knew was both wrong and less than the whole. Similarly my old man said little about his sinking and he was economical with the story too.