In the 1950s, entire 45-aircraft wings of B-47s used to be based in the UK - TDY for 90 days from 1953 to 1958 - with 15 aircraft on alert armed with nuclear weapons.
7th Air Division SAC - HQ at South Ruislip then High Wycombe - controlled Fairford, Brize Norton, Greenham Common and Upper Heyford.
From 1958 to 1965, "Reflex Alert" aircraft were deployed from several bases in the USA to the UK for 21-day deployments - 4 bases above + Lakenheath to 1960 and Mildenhall and some minor dispersal bases like Chelveston and Bruntingthorpe.
In addition, ELINT RB-47Es/Hs were operated from Brize Norton then Upper Heyford until December 1965. I used to see them as a kid at UH - usually in a hangar near the public road with the tail sticking out through a specially fitted opening in the hangar doors.
An impressive aircraft when it first came out and built in huge numbers - 2,032 all marks at an average cost of $1.9M ($16.2M in 2016 $ - not bad at all !).
Some interesting Reflex memoirs in the links here including photos of their alert locations and R&R trips in Europe.
https://b-47.com/?page_id=2890