I thought Mark wrote Sultans in a pub in Ipswich, and I think I probably heard him saying that, on Sultans Of Swing compilation interview or something.
Anyway, it's crazy to think such major details are a mystery. You know where Paul McCartney wrote each song and the colour of the socks he wore, but nobody knows for certain where Sultans Of Swing pub was, who guitar George was, and so on. Unbelievable. I doubt there was even a band like this at all, as you can imagine whoever it was would've embraced the homage and tour with it. Maybe Mark was really drunk and was seeing things.