Whenever I am writing, but feel short of inspiration, I re-read The Day Of The Jackal, the thriller that made Frederick Forsyth’s name, and which was published fifty years ago this year. After my original copy (my parents’ actually) fell to bits I bought another one, which has gone missing. Did I lend it out? Who to? Anyway, a few weeks ago I treated myself to a foxed and somewhat battered first edition, justifying the purchase to myself on the grounds that there is no book I have read more times. On holiday I polished it off again.

I turn to the book because I love its cynical tone, its fusion of fact and fiction, the detail, and most of all its pace. But it must be longer than I thought since I last read it because my own experience of living in Paris, nearly a decade ago, has coloured this most recent reading. As someone who once took a suit to a dry cleaner in the eighth arrondissement at the end of July to be told it would be ready in ‘three working days’ time, on 2 September’, I now admire Forsyth’s evocation of the stultifying climate of the city in August when those Parisians who are rich and wise enough  migrate.

More interesting still (because I was working at the British Embassy), and of persistent relevance, is Forsyth’s depiction of the endlessly prickly Anglo-French relationship, which has recently come under scrutiny again. ‘Good’ or ‘Bad’ do it no justice. The key question is whether, beneath the surface in a crisis, it works. The plot of The Day of the Jackal  hinges on this question.

If you have not yet read the book, it might be best to stop here. Following a referendum in which the French voted in favour of the-then president Charles de Gaulle’s decision to allow Algeria self-determination, a group of diehard army officers set up a terrorist group, the Organisation de l’Armée Secrète. Its aim was to stop Algeria gaining independence by the overthrow of the Fifth Republic, which it would trigger by the murder of de Gaulle. Following the failure of a series of amateurish schemes – and now we drift from reality into Forsyth’s fiction – the OAS’s leader has an idea. Aware how thoroughly the group has been penetrated by the French security services he decides to hire a professional, foreign killer unknown to the French authorities and draws up a shortlist of three names. Of these the German and the South African are ruled out, leaving only one real candidate. Reviewing the CVs his deputy provides the clinching argument: ‘Besides, the Englishman speaks fluent French.’

Much of the first half of The Day of the Jackal is devoted to the assassin’s meticulous preparations. One effect of this, combined with the timing of the book’s initial publication (it came out a few months after de Gaulle had died, of an aneurysm at home while watching television) is to leave the reader wondering how on earth the killer fails.

When the French get wind of the new plot and informally approach London for help, the question of the strength of Anglo-French relations arises, at what was in reality a particularly awkward time for the Entente Cordiale. By setting the story in the summer of 1963, Forsyth places the action in the aftermath of de Gaulle’s infamous press conference that January, when he announced that he would veto Britain’s attempt to join the Common Market. Forsyth, then a cub reporter with Reuters in Paris, was in the room. Joining had been Harold Macmillan’s idea. ‘On the Brussels front’, the British prime minister wrote in the next entry in his diary, ‘everything has been reduced to chaos by the extraordinary behaviour of de Gaulle.’ The consequences were lasting. Immediately after de Gaulle’s death in 1970, the Daily Telegraph condemned his ‘narrow nationalism which misunderstood and despised the post war strivings towards a united Europe.’ And it reminded its readers of ‘the succession of humiliations which he heaped on us in our efforts to enter Europe.’

What would have happened, then, if there really had been a plot to kill de Gaulle in the summer of 1963, and the French had asked Scotland Yard for help? Forsyth, who has since said that his experience in Biafra ‘deprived me of my faith or trust in the senior mandarins of the Civil Service’, invents a particularly unattractive character in the Foreign Office, Sir Jasper Quigley, to voice the idea that Britain should do no more than go through the motions when dealing with the French request.

In the story Forsyth has Macmillan intervene when he hears of Sir Jasper’s views, ordering Scotland Yard to afford the French every possible assistance. ‘Are you aware’, the prime minister asks the policeman he has summoned to Downing Street, ‘that there apparently exist some persons in this country, persons occupying not obscure positions of authority, who would not be distressed if your investigations were to be less energetic than possible?’

Indeed there really were. One of them, Edward Heath, was prime minister when the book was published in 1971. In February 1963 Heath had written of de Gaulle, ‘our ultimate objective must be to persuade him to change his mind or the French to throw him out.’ Meanwhile, just down the road from the Elysée, the British ambassador Pierson Dixon had recommended trying to isolate de Gaulle, in order to ‘contribute to his eventual downfall’. He continued: ‘We can hardly be so presumptuous as to put it among the objectives of our foreign policy to bring about the downfall of General de Gaulle. But at least we can include among the objectives the creation of conditions which will facilitate it.’

Contributing to de Gaulle’s downfall was one thing; a British government would surely not have stood by and let his killing happen. But many readers of the book will appreciate the dilemma that British knowledge of such a plot against the president would have raised. Forsyth’s decision to make the killer British and his target the least popular Frenchman in Britain since Napoleon ensured that many of his early readers felt a perverse impulse to take the assassin’s side. Forsyth has always said he is amazed by this (he says he was naïve), yet by his arrangement of the last part of the book – Macmillan’s honourable intervention and the assassin’s murder of two innocent people in his attempt to remain unfound – he ultimately forces the reader to root for the unremarkable looking, henpecked French detective, whose job it is to hunt the Jackal down.

What might have happened had he failed and the Jackal’s explosive bullet found its mark? Here the strategy of the OAS, and the views of British and French figures coincide. In 1965, having left office Macmillan had a conversation with a former French ambassador to London. France was ‘prosperous enough and enjoying being strongly governed,’ the old diplomat told him. ‘But it will break out when the Emperor dies.’