Sarah Churchwell: What made Alistair Cooke great

Yesterday would have been the hundredth anniversary of Alistair Cooke's birth. For me, as for most Americans over the age of 25, the name Alistair Cooke conjures a familiar image: a grey-haired Englishman, accoutred with smoking jacket, cravat, and pipe, sitting in a wing chair by a crackling fire, introducing PBS's Masterpiece Theatre.

Hosting the television program that brought BBC television to America made Alistair Cooke so iconic there that he spawned parodies and spin-offs, including Sesame Street's immortal "Monsterpiece Theatre," starring Cookie Monster as Alistair Cookie, who ended most of his segments by gobbling down his pipe.

Introducing everything from Elizabeth R and I, Claudius, to minor adaptations like Frederick Lonsdale's On Approval, Cooke explained British high culture to us. He was Englishness personified, as Edwardian as the world of Upstairs, Downstairs he interpreted for us.

It came as something of a surprise, after I moved to Britain, to learn that he is as iconic here, but for the opposite reason: our quintessential Englishman was Britain's voice of modern America for half a century in his weekly broadcast for the BBC. The symmetry pleases: he brought the BBC to us, and the BBC brought him back to you.

The American Studies department at the University of East Anglia, where I work, has just acquired the rights to create an online archive of the nearly 3,000 transcripts of his broadcasts from 1946 to 2004, which came to an end only weeks before his death.

I only discovered the Letters from America once I moved here, and was fascinated by Cooke's vision of my country, for it seems to me entirely English. Restrained, cool, cerebral, distant, Cooke's writing was characterised by an obliquity that is quite alien to the American sensibility. We are a direct people; Cooke's brilliance was to understand our directness and translate it back, indirectly.

In many ways, Alistair Cooke exemplifies the so-called special relationship, the fundamental affinities between America and Britain-and our equally fundamental differences. I once had the experience of expatriation explained to me as the feeling on a good day that you belong to two countries, and on a bad that you don't belong anywhere at all. Reading Cooke's letters, registering the consummate ease and comfort he projected, it is easy to believe that every day was a good day for Cooke.

But the apparent effortlessness that characterises his writing only comes from great effort; consider the almost prophetic foreboding with which he ends his description of John F. Kennedy's inauguration, describing the "warm, remote population that had seen Robert Frost's moment of misery, and Mrs Kennedy's smooth throat twitch for a second as the 'unbearable office' passed from the oldest President to the youngest". The minutiae of that frightening, finely observed "twitch" suggests that his prescience derived from precision, graft disguised by craft.

Understanding that the medium is the message, Cooke crafted his television image as carefully as his words. It seems apt that this most American of Brits should, in fact, have been raised by working-class parents in Salford. His persona as America's favourite aristocrat was conjured in a way that would do any self-inventing American proud. Having sprung in part from a Platonic conception of himself, Alistair Cooke lived the American dream – a greater Gatsby.