Perhaps less well known is that the USAFE carried out a number of overflights of the Warsaw Bloc in 1955 & 1956.
These were shallow penetrations using three RF-100As based at Biturg who relied on speed flying in at 50,000 feet with afterburner and also six RF-57As based at Rhein Main who relied on flying high for safety. It is thought there were about 6 RF-100A and between 15 to 20 RB-57As overflights.
Of course it quite possible that the RAF, using its equivalent of the RB-57, could have carrried out its own overflights but I cannot supply any evidence to support this thesis.