Listed in the 1963 Borough of Mitcham List of Factories as Television set repairs
This 1960 ad is from the Norwood News, via the British Newspaper Archive, which requires a subscription:
The shop can be seen in a photo from 1974 on the Collage website.
Borough of Mitcham List of Factories,
Town Clerk’s Department,
Available at Merton Heritage and Local Studies Centre at Morden Library.
Reference L2 (670) MIT