The best known broadcaster of his age, Alistair Cooke was also its most accomplished practitioner, at least in a studio in front of the microphone.

His Letter from America , which went out weekly from 1946 until earlier this month, was easily the longest-running BBC programme.

It spanned the history of America, from the days of recovery from the Second World War, through the McCarthyite period of the Cold War and the turbulent 1960s, when Cooke personally witnessed the assassination of Bobby Kennedy, to the attacks of September 11, 2001, and the second Gulf War.

Letter from America had its critics - who regarded it as altogether too bland and soft in the predominantly rose-coloured view it presented of the United States - but even among its detractors there was no inclination to deny the sheer professionalism with which it was done.

Cooke's technique - and this was true also of his written journalism - was always to approach his subject at a tangent, moving from some far-off periphery to the core of what he wanted to say.

On the air this turned him into a natural storyteller, the master of the pause and the deliberate hesitation, with the matchless gift of sounding entirely spontaneous when he was, of course, reading from a prepared script.

This was a facility that did not serve him quite so well on television, where he could appear rather measured and mannered.

His 13-part series America, for the BBC in 1972, was an enormous commercial success but did not enjoy anything like the critical acclaim accorded to Kenneth Clark's celebrated Civilization: on the contrary, it was heavily attacked, by academics in particular.

Nevertheless, the secondary television sales from it, and the accompanying book, which sold 2.8 million copies in hardback, made Cooke's fortune.

His consequent renown also brought him an invitation to address a joint session of the US Congress as part of American Bicentennial celebrations in 1974.

The previous year he had been appointed an honorary KBE (he had been an American citizen since 1941) on the nomination of Edward Heath.

What faithful British listeners to Letter from America seldom realised was that its sole author and originator enjoyed an almost equal fame in the country of his adoption, though there it was based on television appearances rather than on radio.