Super Gran (1985)

S01E09 Supergran and the Doppelganger

Greta Garboils, a cunning master of disguise from Glasgow, teams up with the Scunner to execute a series of crimes while impersonating Supergran, with the Muscles taking on the roles of Willie and Edison. However, their scheme takes a turn when the genuine Supergran gets apprehended and finds herself locked up on a diet of bread and water at the Chisleton police station.