Big screen 405 line TV set.

[ppppenguin]

It's well known that there was concern about restarting the service on 405 after WW2. The decision was mainly political and economic - Britain was stony broke and any change would have meant delays in restarting the service. I don't know when London was chosen for the 1948 Olympics but I doubt it could have been televised at all if we'd moved to a new standard.