Training as a civil ATCO at Northern Radar in mid 1973, one day one of the RAF controllers strolled over and told me 'watch track number XX; it's an SR71'
I watched it and noted it would move at high speed for some distance, then the blip would apparently stop (the Type 82 radar I was watching was not equipped with MTI) then it would move again, tracking north west from the vicinity of Alconbury.
It wasn't until later I read about the SR71 climb technique.
The following year, 1974, having been posted to Farnborough I was present when 'Aspen 01' arrived having left Beale only a few hours previously and setting up a world record across the Atlantic.
We were told to have fire crews standing by as if one or more of his 3 brake chutes failed to stream, he would stay down but have VERY hot brakes when he stopped.