It's also worth getting hold of a copy of the video of the Timewatch program that Paul Lashmar produced - thsi was the first public confirmation that the 'British' RB-45s were used in overflight operations. Some interesting interviews with the some of the crew members.
The CIA history of the U2 is avalalble on their website, but all mention of the UK operations is redacted out (at the behest of HMG)
https://www.cia.gov/library/center-f...1974/index.htm
It also mentions the Kapustin Yar operation