Not that one, Gervase. You're thinking of Polychest, the 'Carpenter's Mistake', a post ship that Aubrey had commanded earlier.
The real HMS Leopard had a mixed career. She fired into an unprepared American frigate to compell her captain to hand back some seamen who had deserted. This was in about 1808, and was one of the causes of the American War of 1812.
Aubrey's mixed fealings were that he was not in a frigate (with better opportunities of prize money) or in a line-of-battle ship (which carried more kudos).