Well, it'll all be sadly academic soon anyway, with the impending retirement of the last orbiters.
Although that quote was from a Wikipedia search, Fairford sounds likely. I think from memory the only runway longer than that would have been the A&AEE at Boscombe Down (Showing my age here! It's probably "Bombs-R-Us" or "Cannon Warehouse" now with all this outsourcing of once-proud institutions to civilian outfits, but I digress...)
Interesting discussion though. Thanks chaps.