Colonel James Skinsale was an MP in the early 20th century. He had spent some time in India while in the army. Skinsale was on a boat trip with Lord Palmerdale in that latter's steam yacht. Palmerdale's secretary, Adelaide Lessage and Harker were also on board. The yacht crashed onto Fang Rock and they climbed ashore, where they met the Fourth Doctor and Leela. He described Leela as "not a bad looker".
After everyone on the island besides Skinsale, Leela and the Doctor were killed by a Rutan scout, they went to the lamp gallery. When the Doctor injured the scout with a make shift mortar, the Doctor asked Skinsale if he had any diamonds, but Skinsale remembered that Palmerdale kept diamonds in his pocket, but Palmerdale's body was in the crew room, so Skinslale went with the Doctor to the crew room. Skinsale found the bag of diamonds on Palmerdale's body, and the Doctor dumped all but one of the diamonds on the floor. While he was picking the diamonds up, the Rutan killed Skinsale as its final victim. The Doctor told Leela that he died with honour. (TV: Horror of Fang Rock)
Skinsale was being blackmailed by Palmerdale, who knew a secret that, if made public, would have ruined him. Skinsale was so determined to keep his secret, he sabotaged the telegraph, the only communication to the mainland. (TV: Horror of Fang Rock)