Well might be these guys.
Photos: Boeing 737-86Q Aircraft Pictures | Airliners.net
They started flying out of MAN, where I'm based, about 6 months ago I think.. Not sure how many planes they have, or where they fly from.. Some people say that its the old Excel under a new name.. Who knows..?
That would be a Sunwing aircraft from Canada. Another one operated out of Gatwick this summer. Both aircraft are back in Canada for the winter.