I found a book on special in the local bookshop about SR-71s...I forget the title but it was a great read.
I remember one story about a recon sortie to/near Murmansk...various Russian aircraft launched to intercept the Blackbird, with the usual result...however having made the turn back to the UK, the SR-71 flew passed a missile trail...
...The crew promptly **** themselves, until they realised they'd just crossed their inbound track and that it was a contrail they'd left behind...which puzzled them as they didn't believe contrails were possible at that altitude (FL800+).
Slightly off-tack...are there any SR-71s on display at any of the London Museums?