From the time the television service started in 1936 through to well into the 1950's, electrical interference was a constant menace. The chief culprit was the motor vehicle whose ignition system could cause considerable picture noise and picture tearing. Indeed, television from London was often received well beyond the intended service area but it was interference that destroyed its entertainment value.
Such was the scale of the problem that the B.B.C. produced a short film to try and persuade car owners to have suppressors fitted to their cars. Filmed in various locations around north-west London, the shop featured on the film was on the corner of Edgwarebury Lane and Station Road, Edgware; on Google Maps I think it is now a dry cleaners..
It was not until 1st July 1953 that all new motor vehicles were required to have suppressors fitted as standard. I'm not certain when the film was made, but the narrator (Macdonald Hobley) does say "All new cars are now fitted with suppressors at the factory..." and the fact the shop only shows single channel sets puts the film at 1953-1954.
Eighteen months later new cars were still nowhere near as common as older cars so the problem of interference continued, prompting discussion in the house of commons as reported in the trade magazine "Trader" for the 6th November 1954.