David Benedict on theatre

The first rule of retro-fashion (apart from "Nobody looks good in hot pants") is that if you are old enough to remember wearing it the first time, don't even think about wearing it on the revival. This is incontrovertibly true of the platform shoe, the flared trouser and the nasty print shirt, the three essential items of the Seventies wardrobe.

Frighteningly enough, the Seventies are back in vogue, possibly because too many cultural producers grew up then and are homesick for an era of happiness, ie their childhood. It's a case of post-modernism as deli-shopping ("I'll have a little of this... oh, and throw in some of that"). Contemporary architects divide into two groups: those who had Lego: all pitched roofs and primary colours, and those who had Meccano: steel girders and exterior bolts.

The Seventies signifiers - Abba, Barbie, The Clangers - which we loathed at the time, are now venerated above and beyond the call of duty. All of which provides endless material for university presses who merrily pump out irony-free doctorates, and theatre producers who churn out incessant compilation shows. Any minute now, someone will dream up a musical about Cat Stevens and call it Cat!.

The notable exception to all this untrammelled nostalgia is Simon Moore and Jane Prowse's Up on the Roof (above right), which traces the lives of five friends over 15 years from the late Seventies when they leave Hull University. As students, they were an a cappella group singing Seventies songs, and the music undercuts and underlines their lives, their hopes and disappointments. The songs may be nostalgic, but the tone is anything but. The original West End production was nominated for three Olivier awards but the recent Dutch production misunderstood it entirely: "It was a glitzy Euro-pop spectacle with all the songs sold to the audience" says Prowse. "They're used ironically and spring directly from the action. It's more like The Big Chill with live music."

'Up on the Roof' is at the Queen's Theatre, Hornchurch, Essex (01708 443333)