Ramadan Shallah, 47, the head of Islamic Jihad, is accused by Mossad, the Israeli intelligence service, of ordering the attack by telephone from Damascus. A transcript of the call is believed to have been given to Condoleezza Rice, the US secretary of state.

Abdullah Badran, 21, the bomber, made clear in a videotape he left behind that he was acting on behalf of Islamic Jihad.

Shallah’s role underlines the extent of his transformation from an unassuming PhD student who spent 1985-90 at Durham, writing a thesis on Islamic banking in Jordan.

“He was dour, didn’t smile and was aloof,” recalled Kathryn Crowton, secretary of the university’s economics department. “He showed no leadership qualities.” He was nevertheless a gifted linguist who spoke fluent English as well as several other languages.

Shallah, who was born in Gaza, was already a militant. He had earned his first degree at Egypt’s Zakazik University and in his four years there — sponsored by the Muslim Brotherhood, an Islamic group — he met other future leaders of the Islamic movement.

A further clue to Shallah’s views is provided by his Durham thesis. It calls for the replacement of the western-style banking system by one in accordance with Islamic law, which bans paying or receiving interest.

The thesis begins with a quotation from the Koran, warning of a “war” from “Allah and his apostle” to be waged against those who persist in demanding the payment of interest.

Interest, it goes on to claim, “has a dangerous effect in disrupting the moral and economic structure of society”. It says every bank should have a a supervisory board that would make sure it is acting in accordance with Sharia — Islamic law — and issue “fatwas” (religious decrees).

Shallah moved from Durham to the University of South Florida in Tampa, where he taught Middle Eastern studies and headed the World and Islam Studies Enterprise, a think tank affiliated to the university.

His academic life came to an abrupt end in 1995 with the assassination of his friend, Fathi Shiqaqi, the head of Islamic Jihad. Leaving behind his comfortable life in Florida, Shallah took his place.

Additional reporting: James Meller

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