RADIO / Emergency flares, labours of love: Robert Hanks on a history of the Seventies, From Loon Pants to Safety Pins

After a decent interval, any period of history will lose its horrors and we can get all dewy-eyed about it. At some point in the late 14th century, people in pubs started to chuckle fondly about the Black Death and swap their favourite embarrassing bubo stories. In this century, rigor had barely touched the Sixties before the glowing obituaries were on the press, and it's been hard to take a straight look at that decade since. The Seventies have had a harder time - an era when idealism had run out of steam, the pop scene had become faintly shaming and the clothes reduced the nation to flapping unco-ordination. But like Godzilla, the Seventies have been revived so often that they've begun to look homely and likeable; Seventies anti-chic, subtly recut to look like straight chic, glares from catwalks and magazine covers, and Seventies memorabilia infest the airwaves.

The main infestation has been From Loon Pants to Safety Pins (Radio 4, Friday), a series of three montage features, wittily produced by Liz Jensen. The pleasure has been partly in the nice balance between nostalgia and sado-masochism. Much of the first two programmes consisted of sheepish, joky talk about Zapata moustaches, platform soles, electric blue hotpants, David Cassidy and Pan's People. There were one or two speeches defending the spirit of the age (including a man who claimed that It's a Knockout was hilarious, citing as evidence a game in which people in giant penguin suits slid about on a revolving platform - 'The funniest thing that I ever saw'). For the most part, though, it has been about exorcising ghosts; and these ghosts have flared sheets.

What has really distinguished the series, though, has been the sharp editing. The narrative has moved firmly from post-Sixties idealism through political disillusionment to punk nihilism; but the programmes have worked the way memory does - fractured, episodic, sprinkled with leitmotivs and unexpected connections. Hints of nightmare come and go, before the full horror is revealed - in Part 2, a stray cry of 'C'mon everybody, it's gibbon time' was left hanging, unexplained, for some seven or eight minutes, while the explanation of what the giant penguins were actually doing cropped up much later in the programme, interwoven with John Peel's memories of a sodden horde of teenage girls wading through a lake to get at the Bay City Rollers, while Tony Blackburn travelled up and down in a speedboat driven by a womble.

The final part (repeated tomorrow night) contained one beautifully judged cut - from a skinhead mob screaming blue murder to a BBC announcer calmly remarking on 'Union Jacks waving everywhere - glorious, glorious sight.' For a giddy moment, it sounded like a fawning commentary on a National Front march; then the commentary moved on, and you realised we were hearing the Queen's Silver Jubilee.

The objection to this sort of programme is the way it elevates trivia - in Jensen's pop-culture view of society, politics is lined up alongside clothes and television programmes as another kind of media event. It contrasts oddly with the version of the Seventies in The Brothers (Radio 4, Tuesday), Anthony Howard's chronicle of the trade union movement since the Second World War. Howard takes politics seriously: as he tells it, history consists of the dealings of powerful interests, capital and labour mediated through the political parties, the unions and the CBI. But these great organisations are themselves at the mercy of individuals, with their moods and whims.

This paves the way for an anecdotal version of history that both helps and hinders Howard and his producer, Mark Savage (the team that made The Gang that Fell Apart, a history of the SDP, in 1991). So long as you have the right interviewees with the right stories to carry the larger narrative, it's easy to create the illusion that we're getting the real meat - history at first hand. On the other hand, you do notice the gaps - in particular, while we have senior union figures like Moss Evans and Len Murray, and Labour politicians like Barbara Castle and James Callaghan there seems to be a dearth of senior Tories between Lord Heath and Lord Tebbit. Meanwhile, tonight's final part looks at the Thatcher years: and only a few of the cast are as yet likely to feel up to laughing about the times they had.