Rupert Cornwell: A raw portrait, but why did he tape himself?

Sometimes you truly feel sorry for Richard Nixon. Why should anyone, 15 years after his death, having suffered the greatest disgrace in American political history, continue to be bombarded with irrefutable evidence of his own sins?

More than 2,370 hours of intimate presidential musings are now public. A further 700 hours are likely to be released. They provide a raw portrait of power stripped of flacks and handlers. But one can only wonder: how different, really, are the unfiltered back-stage conversations of others in similar positions: Blair, Brown, Bush, even saintly Obama?

These tapes confirm that for 11 years, between 1963 and 1974, the White House was surely home to two of the most psychologically complex men, fascinating yet repellent, ever to lead a democracy.

Lyndon Johnson was crude, vain and bullying. But he was also a political force of nature without whom the great civil rights legislation of the 1960s might not have happened. Nixon was no less full of contradictions. He was paranoid, petty, as crude as LBJ – but an extraordinarily creative foreign policy thinker, a quality that would have served Johnson well in the morass of Vietnam.

Nixon's morass was Watergate, a conspiracy that fed upon his insecurity, and his conviction – not entirely unjustified – that the world was out to get him.

The greatest question of all remains unanswered. Why did he tape himself at all? Was it a means of blackmailing his close associates – or to provide evidence to rebut what others said of him? In fact, the recordings merely provided confirmation. And without them he would never have been toppled by Watergate.