Silly question, but annoying...1996 9000 CSE 2.3 T....Standard radio cassette. All works fine until I switch on the heated rear screen, then I get a large amount of interference when listening to the radio. All earths and connections to the aerial and radio have been checked and cleaned. Any thoughts why this should happen, I thought that generally, interference was caused by electric motors more than just switching on a circuit?

Check the earth to the rear screen heater. These handle a lot of current and are susceptible to overheating/oxidation leading various odd electrical phenomena. I think if you clean the earth connector your problem will go away.

Derek, I will check the earth as you suggest and report back to you. many thanks