Even before Isaac Newton parked his celebrated behind on the Lucasian Chair of mathematics at Cambridge University, Oxford had been doing important work in applied mathematics for centuries.

The Sedleian Chair of Natural Philosophy was endowed in 1615 by Charles Sedley and is associated with The Queen’s College on the High.

It is to the Sedleian that the great thinkers in applied mathematics go to pursue ideas of such eye-watering complexity that most mortals have not the faintest idea what these people do for a living.

There has only ever been once unfilled vacancy in the long history of the chair and that was in the years between 1940 and 1946.

No one needs reminding that these were the years when the world stared into the Nazi abyss and wondered whether anyone would ever be free again.

That great conflict ended with the detonation of two horrendous weapons: The bombs that destroyed the Japanese cities of Hiroshima and Nagasaki.

These bombs and many others came out of the Manhattan Project, a project that is generally thought of as an American enterprise.

What is less well known is that British scientists were an important component of the project and foremost among these was William Penney.

Penney, a British physicist who specialised in assessments of blast damage, had been educated at Cambridge and Imperial College London.

He rapidly became so important to the Manhattan Project that he was appointed to the target selection committee for the Japanese raids.

Penney was on one of the observation planes that followed the B-29 bomber Bocks Car when it dropped its bomb on Nagasaki on August 9, 1945. Penney later wrote: “All of us were in a state of emotional shock. We realised that a new age had begun and that possibly we had all made some contribution to raising a monster that would consume us all.” This was the bomb that ended the Second World War. A few days later, Penney was walking the ruined streets of the city making measurements of the damage.

Then the war was over and the ex-patriots among the Los Alamos team dispersed to their home countries.

William Penney came back to Britain to personal tragedy — his wife Adele has died in 1945 of complications following postnatal depression after the birth of their second child.

Penney spent several weeks in September and October of 1945 calculating the yield of the bomb that had destroyed Nagasaki.

He did this with the aid of a vast collection of bent poles, crushed cans and twisted metal panels that he had collected from the city and that he had brought home with him. So large was this collection that he had been presented with an excess luggage bill of £450 when he landed at London Airport. In November 1945, Penney was approached by the celebrated novelist and civil service commissioner C. P. Snow and asked to take the job of Chief Superintendent of Armament Research (a job known as CaeSAR). Snow explained that there were already moves in government circles for Britain to develop its own bomb so “they could have a seat at the table” as Prime Minister Clement Atlee put it.

They wanted Penney to head the project. It was an agonising decision for Penney. Like many of the men involved in the Japanese bombings he was not proud of what he had done but had felt it his duty to do it to help bring the war to an end. Now he was being asked to do the same thing all over again.

To complicate matters Penney had that month married Joan Quennell, the nurse who had cared for Adele and their two young boys during the time that Penney had been at Los Alamos.

Penney has also just received a most flattering invitation: to the Sedleian Chair at Oxford, the most prestigious chair of applied maths in the world.

All Penney wanted to do, as he later said, was be a professor but once again duty was calling him.

During their honeymoon in Chipping Campden, Penny talked it over with his new bride — the first and last time he ever felt free to discuss his work with her.

He decided to take the job and turn down the Oxford chair.

For the next seven years Penney laboured tirelessly to develop Britain’s first nuclear weapon.

It was donated abroad the frigate HMS Plym on October 3, 1952 in the Monte Bello Islands off the north-western coast of Australia.

Thereafter Penney, now knighted and a lynchpin of Britain’s scientific civil service was unable to separate himself from Britain’s nuclear bomb program.

He stayed at the Atomic Energy Establishment until his retirement in 1967.

He and Joan had moved to East Hendred, near Wantage, in 1963, where Penney could be close to the dreaming spires that had once beckoned him but still able to commute to the job — at Aldermaston — that had ultimately claimed him.

He was created Baron Penney of East Hendred in 1967 and became rector of Imperial College in London. He retired again in 1973 and thereafter spent his time gardening, golfing and enjoying the company of his grandchildren.

In the 1980s a tidal wave of self-loathing at their previous acquiescence to nuclear testing swept Australia and as history was re-written (for the Australians had originally been enthusiastic partners in the UK bomb project), Penney was called before an Australian parliamentary commission to defend the UK’s use of the sites in the Monte Bello Islands and later in South Australia.

Penney was roughly treated by the commission.

He became depressed and his health which had been failing anyhow — possibly because of his lifetime exposure to nuclear radiation — deteriorated.

He died in 1991 having never become a professor at Oxford as he had so dearly wanted.