Captainyonder.
The distance between Guernsey and Zurich flying upper airways sat Flight level 210 the distance is 471.5 miles.
With the Jetstream as you quote would take just over two hours, I would have at a good guess more like one hour fifty flight time with taxi time at both ends would end up at two hours and ten minutes.
In an executive fit as the Jetstream is would not be to uncomfortable as you just have a single leather seat in each position you never know they might put a hostess on the flight as this would be aiming at a buisness trade at a guess.
Well at least it is a start providing it come off and good luck good to see new blood appearing around in the new year hope it continues.