Lots of background information on British participation in U2 flights on
this declassified Top Secret (Byeman) document
For example
31 Dec 1958 British pilot flies the first operational mission
over Middle East targets. The British fly a total
of 28 missions with Detachment B (4 weather missions
over England, 2 photo reconnaissance missions over
the USSR from Peshawar, and the balance over the
Middle East.)