In my case, the answer to the question “do you remember what you were doing when JFK was shot?” is: probably sleeping or being sick. Eighteen months old at the time of the first Kennedy slaying, I was old enough to ask why my mother started crying when, in a Yorkshire shop in June 1968, a transistor radio confirmed that the second Kennedy had died.

Robert Francis Kennedy is a powerful presence – and John Fitzgerald Kennedy an overwhelming absence – in The Death of a President, a book by William Manchester that I have thought about immeasurable times since first reading it in 1975.

By then I was 13 and we had moved south to Hertfordshire, where I attended a Catholic school run by an American religious teaching order. Our teachers would speak (sometimes tearfully) of having voted for JFK or signed up for his peace corps. As the first (and still only) Catholic to reach the White House, his framed photograph was on the wall of the entrance hall. We played sport against another local school that was actually called John F Kennedy, a measure of the impact his death had made in England.

My dad, a history graduate and obsessive consumer of the news, had a library of books about politics and it was there that I discovered The Death of a President. William Manchester was a newspaper reporter who became a history professor, and in this account of Kennedy’s assassination he combines the highest standards of both professions.

Jacqueline Kennedy had commissioned the book 10 weeks after the murder, although she subsequently delayed its appearance, apparently concerned by private details about family relationships. This pre-publication stumble has led the suspicious to question the independence and authority of the account.

For me, though, any worries about what might not be in the book are over-powered by what is. Its 700 pages cover just five days, from preparations for the flight to Dallas to the burial of the 35th president. Interviewees included all the major players – President Lyndon Johnson, the senior Kennedys and the relatives of the presumed assassin, Lee Harvey Oswald – but also hundreds of minor ones: aides, caterers, undertakers, tourists, hospital orderlies, priests. From these transcripts, Manchester constructs an astonishing multi-viewpoint narrative in sections named after the Secret Service code-words in use on the days in question, including “Lancer” (the president) and “Castle” (the White House).

Manchester seems to have found out everything: not just what people said, thought, ate, and wore, but what was in JFK’s wallet (including the number of his driving licence) and how his widow planned to distract their young son during the funeral.

A teenager who read a lot of thrillers, I remember realising that this book was more gripping than any of them. Subsequent re-readings confirmed my view that this was how the stories of contemporary events – whether in journalism, history or fiction – should ideally be told.

At a direct level of influence, I wrote a novel, Idlewild, and a radio play, London, This is Washington, in which JFK was a character. One of Manchester’s minor but most striking interviewees, Father Oscar Huber, the priest who gave the president the last rites, is a character in my book.

Manchester’s working principle – if someone mentions curtains, ask which colour and, if they were chewing gum, which flavour – disfigured magazine journalism in the US and UK for a while, in pieces that told us more about the soft furnishings than the subject. But the general instinct is correct: tiny gestures and decisions can have massive significance. Interviews are a crucial tool for capturing history and the pursuit of detail should be exhaustive and pedantic.

I was a teenager who read a lot of thrillers, but this book was more gripping than any of them

Although the best American non-fiction writers who came after Manchester – Norman Mailer, Tom Wolfe, Michael Lewis – tended to be brighter stylists, they carried on the understanding that the strength of contemporary history is the availability of primary oral accounts and that the reporter’s major job is to orchestrate and counterpoint these verbal sources. Mailer’s The Executioner’s Song, his magnificent account of the life and judicial killing of criminal Gary Gilmore, is formally divided into sections called Eastern Voices and Western Voices, but the importance of the burning spoken memory equally informs Wolfe’s The Right Stuff and Lewis’s Moneyball and Flash Boys.

Those other great American factual narratives are as much part of Manchester’s legacy as his contribution to our understanding of Kennedy, which, because his aim was to capture the way it was then, has not been devalued by subsequent revelations.

For those who are convinced that Lee Harvey Oswald didn’t kill Kennedy – or that Lyndon Johnson did – Manchester’s book is a travesty and a main supporting column of the establishment cover-up. For more open-minded readers – and any writer aspiring to tell the story of their times in any form – it is one of the few works of history that itself deserves to be described as historic.