But Heathrow aren’t flogging off any of their runways.

Therefore, as per the OP, Macrihanish is indeed the longest runway for sale in the UK. 😀

Yes that is true Grey Area, mind you if things go badly for BAA, Heathrows runways might well be flogged off although I was reading yesterday that Ferrovial will fight tooth and nail to keep it. On the subject of airports for sale, I always thought that shares in Manchester would have been a good buy and back in the mid nineties there was some talk of the airport going public so I wrote a letter to the finance people at – was it Manchester Corporation?? (Can’t remember) enquiring about buying shares and got a blunt letter back saying that they had absolutley no intention of selling the airport or making shares available which was a pity. I have followed the fortunes of Manchester since the mid sixties and it strikes me as being an airport which has always been managed and run by people who are keen to see it succeed.