He made a name for himself in the 1930s in air racing, aged 20, he competed in the Blue Riband of air racing, The Kings Cup, in 1933, in a Comper Swift. winning the Siddeley Trophy. He also flew a Leopard Moth and an Arrow Active which caught fire while he was performing aerobatics. Henshaw bailed out safely. He later moved on to a Percival Mew Gull. He won the inaugural London-to-Isle of Man air race in 1937, and won the Kings Cup in 1938.He then turned to long distance flying, he set off from Gravesend at 0335 GMT on Sunday 5 February 1939 to fly his Mew Gull to Cape Town and back. He spent 28 hours in Cape Town, and retraced his route back to the UK, landing on 9 February after a flight of 39 hours, 36 minutes. He completed the whole 12,754-mile round trip in 4 days, 10 hours and 16 minutes, breaking the record for each leg and setting a solo record for the round trip.At the start of the Second World War he became a test pilot for Vickers Armstrong. He subsequently took the rank of Sgt Pilot to fly a fully armed Spitfire to defend the factory, if needed, although he was never called upon to fly in combat.In June 1940, Henshaw moved to the Castle Bromwich factory in Birmingham, he was soon appointed to the post of Chief Test Pilot, leading a team of 25 others. The factory built over half of the total output of Spitfires ever made, and 350 Lancaster heavy bombers; Henshaw tested both types of aircraft.He also demonstrated the Spitfire to visiting dignitaries, such as Winston Churchill, and once flying the length of Broad Street in Birmingham at low level. He is the only pilot known to have performed a barrel roll in a Lancaster bomber.He was appointed as a Member of the Order of the British Empire (MBE) for his wartime service.