The RAF was not the only operator of Lightnings . . .
Certainly in the '50s the RAF flew USAF aircraft, B45s I think, as Trueman would not authorise USAF crews and they certainly did boder crossings. The 2TAF Meteors used to have to delouse them when they came out. I heard the same of the Victor Training Flight - 1950s version.
Then remember there were Lightnings based in Germany and there may have been attempts to intercept Foxbats or delouse the SR71.
As far as 'North Sea' goes, we used to file 'open' post-reps at Nato Confidential that were works of pure fiction compared with the UK Secret postreps.