Sergeant Leigh was a British Army officer under Commander Millington at Maiden's Point in 1943. He was the guard in charge of Captain Sorin once the Russian was captured, but Ace distracted Leigh while the Seventh Doctor freed Sorin.
He later took a group of soldiers to take the WRNS to safety, but they discovered they had mutated into Haemovores. They swarmed onto Leigh, killing him while the other soldiers fled. (TV: The Curse of Fenric)