Angus Lionel Thornton was an officer aboard Red Dwarf.
Thornton was a physically fit man who was 36 years old at the time that Red Dwarf was recreated by the nanobots. He had a moustache and a small beard. Thornton served aboard Red Dwarf as a security operative, maintaining discipline and punishment for the crew.
Thornton was present when Starbug crashed in the newly reformed cargo bays. He was ordered by Captain Hollister to arrest Lister, Kryten, The Cat and Kochanski and escort them to their quarters. He seemed to take great pleasure in shouting at Lister and making him run to his quarters. ("Back in the Red I")
Inside the Artificial Reality used to determine the truth of the Starbug crew's story, Thornton was in charge of looking for the "escaped" prisoners. He found The Cat, Lister and Kochanski but did not recognise them, as they were disguised as "The Dibbley Family". ("Back in the Red II")
Rimmer then attempted to gain access to the AR suite by using various things that he had learned from the ship's confidential files to blackmail Thornton. He revealed Thornton's full name, age, collar size, inside leg measurement, the fact that he was circumcised, that he was a jazz fan, that he had a good credit rating and at one point had been admitted to hospital stark naked and attached to the suction end of a vacuum cleaner. Thornton agreed to take a 5 minute cigarette break so that Rimmer could enter the suite unseen. ("Back in the Red III")
Behind the scenes
In the scene where Rimmer blackmails Thornton, the line where it is revealed what Thornton was attached to at the hospital was whispered by Rimmer and was not audible. However, the line about the vacuum was scripted and delivered by Chris Barrie.
Technically, Thornton's appearances in Back in the Red parts 2 and 3 were not him, but were instead an AR character designed to look and act like him.
Thornton was credited as MP Thornton, which presumably means Military Policeman.