Aherne began performing on the Manchester comedy circuit as characters such as Mitzi Goldberg, lead singer of the comedy country and western act the Mitzi Goldberg Experience, and Sister Mary Immaculate, an Irish nun. She developed her Mrs Merton character with Frank Sidebottom for his show on Piccadilly Radio, where she worked as a receptionist. Aherne's first TV appearances were as Mrs Merton in a semi-regular spot on the Granada TV discussion show "Upfront" in 1990. She had already recorded a pilot for Leeds-based Yorkshire TV of "Mrs Murton's Nightcap", but they had not pursued the concept. She made brief appearances in "The Smell of Reeves and Mortimer" in 1993 and alongside Steve Coogan and John Thomson in a Granada TV pilot entitled "The Dead Good Show"s.