Complex sentence: Oxford Flying Club was officially opened by the Mayor of Oxford in 1939 however, restrictions placed on civil aviation during World War II curtailed its activities and the airfield operated as RAF Kidlington for the duration of hostilities.
Split into simpler sentences: Oxford Flying Club was officially opened by the Mayor of Oxford in 1939. However, restrictions placed on civil aviation during World War II curtailed its activities and the airfield operated as RAF Kidlington for the duration of hostilities.