Edward Kennedy is today known to the Irish and to most in Britain as one of the heroes of the peace process which eventually brought about the demise of the IRA.

In particular he played a key part in persuading Bill Clinton to take the highly controversial step of lifting the ban which had for decades kept Sinn Fein president Gerry Adams out of the US. That decision is seen as having huge significance in demonstrating to IRA hardliners that ending violence would open new doors and allow them to make powerful new allies.

But Edward Kennedy was not always viewed as a hero: for years he was regarded by London and the Ulster Unionists with resentment and great suspicion. Part of this stemmed from the Second World War when his father Joe, who had been appointed as ambassador to Britain by Franklin Roosevelt, urged the US not to expend energy in helping Britain against Hitler. "Democracy is finished in England," he declared.

In the early days of The Troubles Kennedy himself gave fresh offence by calling for a British withdrawal from Northern Ireland, in what was viewed as the unsophisticated naivety of a young politician. In the years that followed, however, nationalist leader John Hume and successive Irish governments worked hard and successfully on Kennedy, so that by the late 1970s he had switched to the position that the central issue was that of ending violence.

But by the early 1990s the peace process was under way, with Hume and Dublin pressing Clinton to allow Adams into America as a demonstration that politics works. Having spent years strongly opposing Sinn Fein, Kennedy said he was "rather startled" when Dublin and Hume urged him to change his approach and support an Adams visit. Kennedy recalled a three-hour conversation in which Hume "talked with a great sense of moral purpose, with an eloquence and persuasiveness, about the importance of giving peace a chance".

The Adams visit was opposed by the US State Department, the FBI, leading US politicians and most of all by the then prime minister John Major. But Clinton sanctioned it, partly on Kennedy's recommendation. An Irish-American lobbyist said: "Nothing moves on Ireland in the administration without Kennedy having a say. If you want to get progress on Ireland, you get to Kennedy." Major was appalled, refusing to take calls from Clinton for several days, but the episode had the desired effect and the peace process was given vital momentum.