On the day Tony Blair resigned as prime minister, Dr Ashraf Marwan, the billionaire son-in-law of Egypt’s President Nasser, fell to his death from the balcony of his London home. The coroner would return an open verdict – it wasn’t clear whether he jumped, fell or was pushed.

Five years earlier, an Israeli historian, Ahron Bregman, had revealed that Marwan was a spy who had played a crucial role in the 1973 October War. The revelation sent shockwaves through the Middle East and thrust Bregman and Marwan into the centre of one of the most provocative espionage sagas of modern times.