Frederick William "Gunner" Hill (24 February 1889 - 10 November 1959) is best known for his pre-war calculations that showed that the high speed fighters then being developed (notably the Supermarine Spitfire and Hawker Hurricane) would need to be armed with eight machine guns in order for them to become the potent weapons that were crucial to the victory in the Battle of Britain. Captain Hill's technical skills were important in arming aircraft in both World Wars.
In World War I, he trialled methods of mounting machine guns in aircraft, evaluated heavy aircraft guns including the 37mm Coventry Ordnance Works (COW) gun, tested ammunition to be used against Zeppelins including the Brock bullet and designed and developed aircraft gun sights. In the inter-war period he worked at the Air Ministry where he continued to work on aircraft gun sights as well as showing how they could best be armed with the weapons then available.
He made key contributions to the development of the GM2 reflector gunsight that helped the allies gain air superiority over Germany.
His 13-year-old daughter, Hazel helped her father, Captain Fred Hill, put eight guns on the Spitfires and Hurricanes in the run-up to World War II with her calculations. The Hazel’s calculations helped Britain win the Battle of Britain in 1940.
The girl who helped win the Battle of Britain
Hazel’s father, Captain Fred Hill was a scientific officer in the Air Ministry. In the mid-1930s they put forward a specification for the new generation of fighter planes, Spitfires and Hurricanes.
The plan was for the planes to have four guns, which was a huge step up from the biplanes of the First World War, which typically carried only one or two. However, Fred had analysed firing data and realised that four guns would not be enough to bring down the increasing well-armoured German planes.
He faced stiff opposition from his superiors at the Air Ministry – the idea of eight guns was seen as staggering, and many felt they would weigh down the new planes and it would be impossible to fit them on.
But Fred was convinced he was right, so he went home armed with one off the latest calculating machines and the latest gun firing analysis – and asked his daughter Hazel, who was a 13-year-old schoolgirl, to help him prove his case.
Together they worked through the night on complex calculations which proved that each plane would need to carry eight guns, firing at least 1,000 rounds a minute to bring down the German planes.
Fred used Hazel’s calculations to create two graphs which he presented to the Air Ministry at a crucial meeting on 19th July 1934. As a result, the plane specifications for the Spitfires and Hurricanes were changed from four to eight guns.
Six years later during the Battle of Britain, eight guns was only just enough for us to win. If we’d gone with four, or even six we would have likely lost the battle.
How Hazel’s contribution was recognised
Fred Hill told only his superior officer at the Air Ministry (Claude Hilton Keith) before that crucial meeting on 19th July 1934, of his daughters help in his crucial calculations. C.H. Keith documented her contribution in his memoirs, which were later published in 1946, and in private correspondence with Fred.
Hazel saw the first prototype Spitfire on display at the Hendon Air show in June 1936. As a thank you for her work, she was given permission to sit in the cockpit of the new plane.
A prestigious career in medicine
During the war, Hazel Hill joined the Royal Army Medical Corp where she treated soldiers who were wounded in the Blitz and fighting overseas. She eventually married one of the soldiers she’d nursed back to health, and they moved to Staffordshire where she became a GP. She went on to become a child psychiatrist, doing pioneering work in school phobia, anorexia and autism. She was hugely proud of her medical career and would definitely want to be remembered for that – but I think history will remember her for this.