I read this thread with some amusement, although I work for ATC and corporate aviation is just a on-the-side interest of mine. Always good to hear what goes on (allegedly) in the corp flight ops depts worldwide.
Apparently a Global visited Luton at the end of Feb 2011 on a QTR from Dorval, and reportedly had the reg G-GJCB under it's C- number. (Though I think this may already have been used on a Hawker).
However, I also heard on reasonable authority they have an early G650 del position.
No doubt there are people on here that know more than I, but I thought I'd throw it in.
Cheers