Complex sentence: However construction did not commence on the airfield until April 1939-the construction was accelerated because of the Second World War, when the Air Ministry instructed the English Electric Company (EE) to proceed with the construction of flight shed number 1.
Split into simpler sentences: However construction did not commence on the airfield until April 1939. And the construction was accelerated because of the Second World War, when the Air Ministry instructed the English Electric Company (EE) to proceed with the construction of flight shed number 1.