The maths whizz who helped prevent disaster

Eileen Younghusband (nee Le Croissette) had a number of jobs when she left school at 16. She worked as an au pair in France, for a bank, and in a factory that made lipstick cases. But after her favourite cousin was killed during pilot training, she felt compelled to join the war effort. In 1941, she enlisted with the Women’s Auxiliary Air Force (WAAF) – she was just 19.

Like many women offering their services during the war, she expected to be taken on first as a cook or a driver. But after revealing her aptitude for mathematics she was taken on as a special duties clerk, working in the Filter Rooms – the top secret hubs of Britain’s air defence.

In these dark, cramped rooms, ‘plotters’ – mainly WAAF personnel – worked long, tiring shifts as an early form of air traffic control. But there were no computers or technologies to help. Instead, it was up to Younghusband and her peers to filter the many reports received from radar sites, observation posts and radio messages to create a coherent picture of the situation in the skies.

A shortage of fighter aircraft and trained pilots meant they had to work quickly, and there was no room for error. This ‘air picture’ was always changing and required constant updates. It was detailed, complicated work.

And it was life-saving work. Guidance from the Filter Rooms helped direct pilots to the enemy, predict where air raid warnings should be sounded, and where rescue boats should be sent to retrieve Allied airmen. Younghusband was in the room during the Normandy landings, and took the coded warning of the first V2 rocket attack on London. She and her team were the lynchpin of air defence.

In the summer of 1944, she was assigned a critical mission: travel to Belgium to determine the launch sites for Hitler’s V2 missiles – the world’s first long-range guided ballistic missile. These weapons (known as ‘Vengeance 2’) were deadly, and were having a devastating impact on British cities. Attacks from V2s had resulted in the deaths of an estimated 9,000 civilians and military personnel, and a further 12,000 forced labourers and concentration camp prisoners died as a result of their enforced involvement in the production of the weapons.

These rockets could be launched from almost anywhere thanks to specially adapted lorries, making them highly mobile and very difficult to detect. They were also impossible to intercept once launched. Younghusband’s job was to track them down so they could be destroyed before they were fired – and she was equipped only with her mathematical skills and a simple slide rule. Despite their limited resources, the WAAF was successful, and by March 1945 every V2 missile had been neutralised.

After Victory in Europe Day (VE Day), when the Allies accepted Nazi Germany’s unconditional surrender – Younghusband worked as a translator at Belgium’s Breendonk concentration camp, using her language skills to learn and report on the horrors that took place there during the war. She resigned from this harrowing post six months later.

But her efforts in the Filter Rooms – and then in the field – saved countless lives, and the outcome of the war may have been very different had Hitler’s devastating V2s not been intercepted. Having signed the Official Secrets Act she was unable to speak about her work for 30 years, but eventually published a range of books detailing her wartime contribution, including two autobiographies and a book for children.

After the war, she continued her lifesaving work by campaigning for health and education issues, and after completing a degree at the age of 87, was awarded the British Empire Medal for her activism against cuts to adult education. She passed away in 2016, aged 95.