Journalists will turn up to the launch of almost anything, provided there is free food attached, but Tate Britain excelled itself for a breakfast preview of its 2005 summer show, "A Picture of Britain". To acknowledge the differing regions represented by the exhibition, which assesses British landscape painting from the 18th century to today, there was kedgeree, bramble jelly on crumpets, sausages and smoked salmon. A six-pack of hot cross buns, representative of the ill-fed London family (step forward, junior Millards), was noticeably absent, but then we were told that the show won't go in for urban vistas.

What it has gone in for is an unusually close relationship with BBC1. The BBC is fond of snuggling up to galleries about to put on a major retrospective, usually in order to produce an attendant biopic - as well as other benefits, it relieves the broadcaster of having to make all those tortuous picture requests. But A Picture of Britain, the six-part TV series, has been carefully plotted alongside plans for the exhibition and, we were told, is the first such collaboration between the two public bodies.

It's a clever way for each to achieve maximum effect. The Tate show's visitor numbers will doubtless be increased by the BBC's (probably) Sunday-night "landmark" show, presented by David Dimbleby. Meanwhile, in the run-up to charter renewal, the BBC will gain from the kudos of being associated with one of the UK's greatest collections.

Both institutions are playing with a very straight bat. There will be no wacky stuff with dead horses or unmade beds at Tate Britain; and BBC1 - perhaps reacting oversensitively to concerns that Alan Titchmarsh's gallop around the UK was culture "lite" - is at last daring to be serious about art history. Constable, Turner, Nash: all the heavyweight daubers are there, plus some who may seem to have less artistic credibility but who still suit a rousing Dimbleby intro. Watercolours by Winston Churchill, anyone? There's even a moment when Vera Lynn is hauled out of storage and gently prompted by her only rival for Voice of the Nation (that's Dimbleby) to warble on the white cliffs. This is the sort of thing you could have imagined sitting down to watch en famille in the choice-free 1970s, which doesn't mean it will be dull, but does mean it will probably be worthier than, say, Channel 4's coverage of the Turner Prize.

Mercifully, what one might call the Rolf Harris style of programming (Van Gogh was a nutter, etc) has clearly been abandoned in favour of loftier role models. At the press launch, Dimbleby admitted he had been reading Kenneth Clark to get in the mood for leading the nation out of the slough of celebrity mania and on to the sunny uplands of cultural understanding, though there will be no shots of him spouting about art in a gallery. No, Dimbleby speaks about Constable while walking through a meadow, and gets wet on a rather perilous-looking boat while doing pieces to camera about Turner.

Will it work? The exhibition will enhance Tate Britain's attempt to be synonymous with a notion of our national culture, while the television series looks glossy and intelligent, and gives British art the kid-glove treatment that the medium has long given French and American painting. It's just a shame it will be transmitted in the summer, thus negating the need to draw the curtains and turn the lights off.