For from life as a backbencher – in which, contrary to myth, he was diligent and energetic, both in Westminster and Hartlepool – he was propelled into the Blairite inner circle. A circle which, thanks to the traumatic period after Smith’s death in 1994 in which Mr Mandelson eventually backed Tony Blair rather than Gordon Brown for the leadership, carried with it what Mr Mandelson himself described as the “great boulder” of the enmity between himself and the Chancellor. At least twice Mr Mandelson offered his “resignation” from his role as an adviser to ease these tensions; at least twice Mr Blair won him round, determined to retain the services of what Tom Sawyer, the party’s general secretary, called the best political strategist of his generation.And that remained part of the problem. For Mr Blair kept him, longer perhaps than for his own good, in jobs which were not as satisfying as a department of his own would have been, but which kept Mr Mandelson close to the centre – and to himself.Outside the Cabinet, but being perceived, not wholly fairly, as having a “mission to meddle”, he found his actual ability to deliver constrained. And while Mr Blair’s lieutenant had told a journalist in the mid-1990s that the Labour Party would not be truly modernised until it had learnt to love Peter Mandelson, his failure to be elected to the party national executive in September 1997 suggested that it had not done so. The one exception to these frustrations, ironically, was the Dome into which he threw himself with characteristic energy, keeping it – despite the doubts about a possible conflict interest among some civil servants – when he went to the DTI.

His failure to notify senior officials of his loan from Mr Robinson when he was appointed Trade and Industry Secretary would cost him dear when it came to light six months later. But in that short period he breathed new life into a department which had become something of a backwater.Mr Mandelson’s notoriety as a flamboyant public figure has always disguised his professionalism and flair as a departmental minister. His crowning achievement, a Competitiveness White Paper foreshadowed many of the incentives to entrepreneurship subsequently enacted. His spectacular pre-Christmas resignation was openly mourned by officials at the DTI.In a sense, his resignation took him back to the backbench career which John Smith’s career had cut off. Although he continued to be consulted by Mr Blair, he kept a relatively low profile. And by the time he returned to the Cabinet as Northern Ireland Secretary in October 1999 he was a maturer – and thanks to a steady relationship with his partner Reinaldo Avila da Silva – personally happier man.There is no reason to doubt his affirmation outside No 10 Downing Street yesterday that this was the most fulfilling challenge of his career.

He worked closely with and won the respect of the leading officials in the department. The moment when he ushered in devolution in December 1999 was, despite the ominous portents of its fragility, a historic moment.His decision to suspend it in February to prevent the collapse of David Trimble’s leadership of the Ulster Unionists provoked a huge backlash from nationalists and republicans. The attempts to demonise him were part of a drive to wedge between himself and Mr Blair But in fact Mr Blair had been closely involved. And it was vindicated when the IRA agreed to open up its arms to inspection and the assembly and executive were restored.He will be a big loss as Northern Ireland Secretary partly becaue of his immersion in its political complexites but also because he was known to be close to the Prime Minister But his departure will have a wider political impact.