Before Thurleigh closed, I used to live in St Neots, which was just south of the extended centre line for the looooooong runway there, and used to regularly see aircraft on long finals, presumably testing out ILS or other approach systems. I believe that the new runway was aligned that way because the previous SW-NE runways would have put the extended centre line straight across both RAF Alconbury and RAF Wyton, a few miles to the north of St Neots. Not a healthy idea, given that these two stations were chucking up a mixture of F4's, A10's, F5's, TR1's, Canberras and Nimrods during the mid to late eighties!
The original standard pattern of three runways is clearly visible, two of which show the wiggly black lines of the race circuits at Jonathan Palmer motorsport, and the remains of the third can be seen going NW-SE. The fourth runway (south of the three, but parallel to the NE-SW runway) I believe was added post war, prior to the big one being put in some time later.
Apologies if that's a bit vague, just going from memory - my old Air Training Corps CO was an ATCO there for his day job, and told me all about the history of the place, but that was nearly twenty years ago...!
BM