Complex sentence: After flight refuelling trials, three Harrows were operated by Flight Refuelling Limited and refuelled Short Empire Flying Boats on transatlantic services, two from Gander, Newfoundland and one based in Foynes, Ireland.
Split into simpler sentences: After flight refuelling trials, three Harrows were operated by Flight Refuelling Limited. They were used to refuel Short Empire Flying Boats on transatlantic services, two were based in Gander, Newfoundland and one based in Foynes, Ireland.