The States of Guernsey-owned Aurigny is the dominant carrier at GCI with direct routes to Alderney, Bristol, East Midlands, Gatwick, Stansted, Manchester, and seasonal routes to Leeds-Bradford and Norwich, plus Dinard and a seasonal Grenoble.
Flybe does Birmingham, Exeter, Southampton and Jersey, with seasonal routes to Cardiff and Zurich.
Air Corbiere operated from Guernsey to Liverpool with some services routing via Coventry or Gloucestershire. They had metroliners, I went on it once great flight and was well received.