Arnold (also known as Arnie) was a member of the British resistance in an alternate timeline who was also an informer for the Britischer Freikorps. While at the Festival of Britain in 1951, he overheard the Seventh Doctor and Ace talking about stopping Hitler and informed Lieutenant Anthony Rupert Hemmings, who arrested them. The next day, he came to Ma Barker's café to warn her and Popplewell of a Freikorps raid; when he saw Ace there, he told Barker and Popplewell that she and the Doctor were working for the Freikorps, while she in turn accused him of turning them in. Hemmings then raided the café, but before he could arrest them, the Doctor arrived with General Otto Strasser and claimed that the four were double agents working against the resistance. (PROSE: Timewyrm: Exodus)