[2] This true story was also later to form the basis behind Michael Ondaatje's Booker Prize-winning 1992 novel The English Patient and the 1996 Academy Award-winning film of the same name starring Ralph Fiennes.

And Eppler did request assistance from the Cairo-based Free Officers Movement, who were at the time nominally pro-Axis in the belief that they would 'liberate' Egypt from the British, and specifically from the young Anwar Sadat.

[5] In contrast, Follett's Wolff – though having a sensual and pleasure-loving side – is completely dedicated to his mission, driven by a curious mixture of German nationalism, Egyptian patriotism and an overwhelming personal ambition.

Like the German spy Faber in Follett's earlier Eye of the Needle, he is supremely intelligent, competent and resourceful, and utterly ruthless – ever ready to kill anyone perceived as threatening him, and preferring to do it silently with a knife.

A departure from cryptologic sense occurs in Follett's title conceit: the "key" or code sequence used to render the Axis spy's messages unreadable by the Allies without it.

[6] The Key to Rebecca was an immediate best-seller, becoming a main selection of the Book of the Month Club, with an initial printing of 100,000 copies within days and having been serialised in several magazines, even before any reviews had been published.

[7][8] Len Deighton's novel City of Gold is set in the same time and place and with a similar theme – the British worried about a spy in Cairo sending information to Rommel.