The funeral will be held next week of a North-East academic whose genius helped to save throusands of lives during the Second World War. Gavin Havery profiles one of the war's unsung heroes.

A MILE above the ground, Tom Willmore's heart froze when he heard the air raid siren. The wailing noise meant that Luftwaffe pilots had been spotted flying over Britain and the enemy aircraft were coming his way.

The brilliant young mathematician - who had gained a degree aged only 16 - had good cause to be more worried than most.

As the mournful wail carried through the air, he found himself strapped to the fin of a 66ft-long balloon filled with 20,000 cubic feet of explosive gas floating high above the ground.

To prevent it floating away on the breeze, each balloon was tethered to a wagon by a cable that could have pulled him to safety.

But when he called control to get him down, Professor Willmore realised everyone was in an air raid shelter.

Fortunately for him - and the Allied war effort - the siren turned out to be a false alarm.

For had Prof Willmore lost his life, strapped to the prototype on that day, the barrage balloon may never have been created and countless British lives would have been lost.

Prof Willmore was the person who calculated the exact height the balloons needed to achieve if they were to prevent Nazi bombing raids.

He also worked out the tensile strength of the cable needed to tether the balloons and destroy any aircraft that flew below them.

He died on Sunday, aged 85, following a long and successful career crunching numbers that saw him become Professor of Mathematics at the University of Durham.

The barrage balloon has 24 confirmed enemy aircraft kills to its name. It also brought down hundreds of enemy rockets.

But more than that, the deterrent value of the balloon was incalculable. They came to be an iconic symbol of Britain's defiance and were a comforting sight to many people who looked up at the skies.

But not satisfied with refining the balloon concept, Prof Willmore also became the first scientist in the UK to study an unexploded V1 flying bomb. He took hundreds of measurements that helped work out the altitude at which the rockets flew.

Armed with that information, the RAF was able to deploy its barrage balloons at the right height to destroy them.

The information helped stop more than 750 V1s aimed at London and the South.

Last night, his wife, Dr Gillian Willmore, said: "He was very brave in his work and very adventurous as a person.

"He was a wonderfully humane man. He had a great mind and a great sense of humour. He also liked to take risks."

Born in Gillingham, Kent, Prof Willmore grew up in Essex before going to University College of London to do a degree in mathematics, aged only 16.

As a teenager, he joined RAF Cardington, in Bedfordshire, as a scientific officer and designed the barrage balloon defence system. He also did his first PhD "in his spare time", earning him the nickname, Doc.

In 1946, he left the services to become a lecturer at the University of Durham while his first wife, Joyce, a well-known artist, brought up their daughter, Helen.

Prof Willmore went on to complete a second Doctorate of Science and was given an honorary PhD from the Open University in recognition of his research.

As an academic, he was widely regarded for his work, which included five books on differential geometry.

It earned him respect with peers across Europe and became a member of the Royal Society of Belgium.

Before his death, he received the Ameritus Leverhulme Fellowship for his ongoing work in defining the present state of differential geometry.

Durham University is now setting up a trust fund for students of pure mathematics.

Colleague and friend Dr John Bolton, senior lecturer in the Department of Mathematical Sciences said: "Tom will be remembered by countless students for his exuberant lecturing style and his enthusiasm for mathematics.

"This, together with his lively sense of humour and his gift for communicating, came over very strongly whenever he lectured and at whatever level."

* His funeral will be held on Monday at 11.45am at Durham Cathedral, followed by committal at the cathedral then refreshments for friends at St Mary's College, Elvet Hill Road in Durham.

Family flowers only, but donations can be sent to University of Durham Willmore Fund, PO Box 43, Durham DH1 3YA.