On a cross-Channel ferry at the start of her honeymoon, my mother met Clement Attlee. In those innocent days, there was nothing odd about a former prime minister exchanging a few words with a stranger as the two of them queued for a cup of tea and a rock bun. Some ministers were protected but no one took the process very seriously. When he was home secretary in the mid-1960s, Roy Jenkins suggested that the uniformed policeman who was detailed to stand outside his door might come inside and make himself useful as a part-time footman. 

All this ended with the launch of an armed struggle by the Provisional IRA in 1969. The number of British politicians who were killed by republican groups was small, but British politics was changed for the worse. Politicians associated with Northern Ireland, defence, home affairs and justice – and, a fortiori, the prime minister – could no longer walk the streets or strike up casual conversations. Ministers became ever more remote from the people over whom they ruled; any intelligent person who wanted their family to have a tolerable life thought twice before going into politics.

Margaret Thatcher suffered badly in the new climate. Two of her friends – Airey Neave and Ian Gow – were killed by Irish republicans. More dramatically, the IRA came close to killing her when one of their volunteers, Patrick Magee, planted a bomb at the Grand Hotel in Brighton. It exploded in the early hours of 12 October 1984, a few hours before Thatcher was due to give her address to the Conservative Party conference. Thatcher emerged more or less unscathed but five people were killed and several more were horribly injured.

Rory Carroll puts the bombing in a long-term perspective. He looks at the origins of the Troubles and the difficult background of Magee himself, who was largely brought up in England. For the most part, though, he concentrates on the period after 1979 – the year in which Thatcher was elected and the IRA assassinated Lord Mountbatten (a great-grandson of Queen Victoria who had been viceroy of India) with a bomb placed on his fishing boat, which also killed three other people, two of them children. He describes the hunger strikes of the early 1980s, as IRA prisoners starved themselves to death in protest at the conditions in which they were held, and the bombing campaign both in Northern Ireland and on the mainland. 

The book is marketed as ‘a blend of true crime and political history’. Most true crime writing takes crimes that are obscure or opaque and uses them to illustrate wider points about the society in which they took place. There was, though, never much mystery about the Brighton bomb. Many understood what had happened as soon as they heard the bang. Magee was eventually arrested and convicted but he was released from prison after the Good Friday Agreement. He wrote a book and spoke freely about what he had done – he once lectured to undergraduates in my own department. Carroll has conducted over a hundred interviews but he does not really have much to add to what we already know about the Northern Ireland Troubles. At times, his account is padded with banal detail. We are told twice that down the corridor from the room in which Magee was setting the bomb, a guest was paying a photographer ‘to take erotic portraits of his female companion’. One sometimes senses that an author desperate to reach his daily quota of words is raising his eyes to heaven: ‘an azure sky unfurled over the Atlantic’; ‘the sun hung in a cloudless sky over London’; ‘a patch of sky [was] paling over the Palace Pier.’ 

But the pace picks up once Carroll gets to the bomb going off. Disregarding warnings that the building was likely to fall down, firemen went to extract the wounded. Norman Tebbit and his wife, Margaret, hid the scale of their injuries from each other as they grasped hands under the rubble – though Margaret, a nurse, had probably guessed that she would be paralysed for life even before rescuers dug her out. Survivors of the bombing gathered in the street in their pyjamas. Alan Clark wrote excitedly in his diary that IRA snipers could have picked off ministers – in fact, the IRA had resorted to a bomb partly because they did not have enough good marksmen. Almost four thousand rubbish bins were used to take the wreckage of the hotel away for examination by forensic scientists. As for Magee, he lay awake in Cork on the night of the blast. Only when the radio news reported the explosion could he get to sleep. He heard that he had failed to kill Thatcher but was relieved that his handiwork had been up to the job. A few hours later he sat with a pint of Guinness, feigning indifference as he watched reports on cable TV in a pub. 

The police discovered that one of the guest cards had been filled in under a false name. They feared that it might just be some adulterer on a dirty weekend, but eventually lifted a fingerprint from it and matched it to Magee. By the time they tracked him down, he was living on a rough Dublin estate. Now the British authorities were in an awkward position. The Irish government cracked down hard on the IRA but Irish courts were independent and unlikely to allow the extradition of a man accused of a political offence. The British concealed the fact that they had identified the bomber and hoped he would eventually feel safe enough to return to the United Kingdom. They got their chance in 1985 when Magee was sent to the mainland with an IRA unit planning to bomb seaside resorts. He was arrested in a Glasgow flat and police found a list of targets hidden on one of his associates. They also disabled a bomb that had already been planted in a London hotel. Magee’s counsel, a former Ulster Unionist politician, did his best, trying to persuade the jury that police had faked evidence. It was true that policemen had beaten confessions out of innocent Irish people in the 1970s, but they seem, this time round, to have treated guilty people with scrupulous correctness. 

Magee got a life sentence with the recommendation that he serve at least thirty-five years. As it turned out, he was released after thirteen. He said nothing at the trial except to shout the words ‘our day will come’ in Irish as he was taken down to the cells after the verdict had been given. He derived some satisfaction from the fact that his reputation as a skilled bomb maker had been confirmed.

What of the consequences? If the prime minister had been killed, her successors could never have been seen talking to Gerry Adams and Martin McGuinness and politics in Northern Ireland would have been frozen for a generation. Understandably, Norman Tebbit never forgave the IRA but he was, beneath the carefully cultivated displays of thuggery, a subtle man and he did not try to impede the moves that the Thatcher government made towards an Anglo-Irish agreement, which, in turn, laid the way for a kind of peace settlement in the 1990s. In the short term, the bombing may have helped Thatcher. It contributed to her image of almost supernatural invincibility. Six months after the Brighton bombing, she won her biggest success in domestic politics when the striking miners threw in the towel and returned to work. The privatisations that Tebbit had lauded in his speech on the day before he was injured went through. But there was a curious sense in which the IRA did kill Thatcher at Brighton. Magee and his comrades described the high-security units in which they were imprisoned as ‘submarines’, because they were so cut off from contact with the outside world. Thatcher’s own security team put her in a submarine of sorts, and it was one that dived ever deeper after Brighton. Isolation from ordinary life was one of the things that accounted for the erosion of her political instincts in the late 1980s and, eventually, her fall.