AS a boy growing up in the 1950s, Peter Stothard was not interested in collecting cigarette cards or trainspotting.

Nor, for instance, was he drawn to sport, to which, he says, to this day he feels "rather allergic". His obsession, which it's perhaps fair to say was not shared by many of his peers, was Cleopatra, the queen of Ancient Egypt, lover not only of Julius Caesar but also of Mark Antony, by the two of whom she had four children.

As Stothard relates in Alexandria: The Last Nights Of Cleopatra, he was eager to translate his enthusiasm into print. His original attempt was made in 1960, when he was nine. All that survives of it is a title, Professor Rame And The Egyptian Queen. This was the first of numerous attempts to capture Cleopatra in print. Finally, in 2011, he achieved his ambition, after spending three weeks in the Hotel Metropole in Alexandria disentangling the tragic queen's mythic story.

As Stothard was leaving, the Arab Spring was beginning. But while the country was coming to the boil, he sat in his room or in cafes sifting through memories and drawing on a lifetime of accumulated knowledge. "I wouldn't have written as much if I'd gone out more," he says.

Stothard, 62, is a former editor of The Times who, for the past decade, has been at the helm of the Times Literary Supplement. We meet in its office in London's docklands.

The TLS seems to suit Stothard to a T and now that he's got the sphinx-sized albatross of Cleopatra off his back, he can ponder why it took him so long to produce a book he may have been predestined to write.

As he says, "the facts of her life are not going to fill many pages". Stothard's solution is to weave together his life and that of Cleopatra.

To achieve this it was essential he take up residence in Alexandria which, astonishingly, he had never previously felt the need to visit. "I'm not much of a tourist. I'm not one of those people who go around with a Baedeker."

He chose to write the book as if he were keeping a diary and acquired two self-appointed guides to the city, Mahmoud and Socratis, both of whom come and go like shady characters in a novel by Graham Greene and about whom Stothard came to know very little. Had he been on a reporting assignment, he says, he might have inquired more of the pair. As it was, it suited his purpose to allow them to flit in and out of the narrative, their motives for helping him unclear and ill-defined.

A third ghost is that of friend Maurice who was another foil for Stothard. The two grew up together and continued to see other throughout their lives. When Maurice was diagnosed with a cancer not dissimilar to the one which Stothard was told was likely to be terminal in 2000, they grew closer.

"He was my oldest friend," writes Stothard. "We shared little in common, he the smooth one, I the rough, he the pale-faced, I the freckled, he the teller of jokes and tales, I the listener. But without always liking each other, we knew each other from the age of four. We shared primary and secondary schools, ... and we also, for a short while, shared a passion for a dead queen of Egypt."

Stothard's family lived on an estate near Chelmsford, Essex, built by Marconi, by whom – in the era of the Cold War – his father was employed as an engineer. His mother was more intrigued by status than the possibility of armageddon which, reckons Stothard, was typical of her class at the time.

Summer was "the great unequaliser". There were three nearby resorts: Clacton-on-Sea, Walton-on-the-Naze and Frinton. Maurice's family went to Frinton which had no fish and chip shops, a sign of its social superiority. Clacton was deemed vulgar and therefore to be avoided. Stothard's family went to middle-of-the-road Walton.

There were just five books in the house, recalls Stothard, one of which, the second volume of the Aeneid, was to unlock for him the door to another world. At school, one classics teacher hissed derisively at pupils who studied German instead of Greek. "It was not so unlike Alexandria, having few ideals beyond respect for power and the encouragement of only such creativity as was properly approved."

Thus two different times and places – postwar Britain and pre-Christian Egypt – are united. It was not, suggests Stothard, how he intended things to work out. On occasion, in Alexandria: The Last Nights Of Cleopatra, he appears surprised that he is so much part of the queen's story and vice versa. But he finds it impossible to disentangle himself from her. That's perhaps the nature of biography, as biographer and subject cease to be separate individuals and somehow become related, in the process forming a new category of literature in which the biographical and autobiographical are one and the same.

"There are lots of conventional ways to tell a life," Stothard says. "But feeling I had to do it at that time, you do it the way it comes, and the way it comes is not necessarily the way it would be constructed in the biography schools."

Alexandria: The Last Nights Of Cleopatra, published by Granta, £25