Arts: The Rolf Harris factor: It pays to have a sense of humour about your image (even more so if it's laughable). Just ask Rolf Harris. Or Jim Bowen. Or Lulu. Just swallow your pride and cash in on post-modern irony. Jim White grins and bears it

Even Take That have caught a dose of it. When their British tour opened at Glagow's SEC on Thursday night, the young Mancunians had, they said, developed the best stage show of their career. There were pyrotechnics, there were micro shorts and bare buttocks, there was a wardrobe load of leather paraphernalia. And, in the finale, raised up above the boys' Chippendale- broad shoulders and wrapped in a lace dress, there was Lulu.

Apparently, it was claimed, the Take That lads had admired Lulu's shouty larynx for years. But that wasn't really why she was invited to join them on stage. Naff long before most of Take That's audience was born, Lulu was up there for one reason only: the humour value. As the magazine Modern Review would put it, she came in inverted commas. Take That had caught irony.

It is now almost impossible to turn on the television and avoid irony. The schedules are furred up with shows picking over the bones of popular culture, resurrecting the second-rate of comedy, pop and fashion and re-presenting it with a knowing smile. Short of a joke? Then get someone in from the Seventies and laugh at them.

Thus there's Gag Tag, in which the mere appearance of humour-free zones like Frank Carson is apparently sufficient to send the studio audience into hospital-alerting spasms of laughter. There's Room 101, which, although the host Nick Hancock is as clinical as anyone with a one-liner, relies for much of its impact on the expectation that the word Smurf will have trousers rushed to dry cleaners across the country. And then there's anything involving Danny Baker, the main instigator of the let's- laugh-at-the-way-we-were-when-we-wore-

Alan-Sunderland-frizz-perms school of humour.

This may not be the first generation to look back in ribaldry. But it is surely the first to allow whole careers to be built on the retro-giggle. And worse, rebuilt. Never before can the objects of hindsighted derision have been so actively encouraged to join in - and cash in - on the joke. Lulu is just the latest in a long line of those who have seen the chance to make a bob or two from all that post-modernism flying around the place.

Many of those discovered by a new audience know perfectly well what their new fans are up to. Jim Bowen, the 58- year-old darts comedian, for instance, who last spring undertook a Bullseye tour of university campuses, makes no secret of the reason students turn up to see him. 'Thank you very much for that marvellous welcome,' he once told the audience at the Oxford Union, which was hanging from the rafters chanting his name. 'Although I cannot help but feel you are taking the piss.'

Rick Wakeman, the caped keyboarder of the Seventies, has forged a new career as a chat-show guest, laughing about his old one as a pomp-rocker. His appearance on Victor Lewis Smith's quiz show Buygones, playing a Yes number on one of Rolf Harris's cast-off Stylophones, was so awash with pop-culture self-references it was almost drowning. But it was also the funniest sight of the year.

And there's Tom Jones, who, since his re-appraisal at the hands of Jonathan Ross, appears not to mind that these days knickers are as often thrown at him in irony as lust: he knows that the owner of the under-garments still has to pay for the privilege of hurling them.

But the real problem with all this is when the revived has-been mis-reads the signals and thinks that they have something new to offer. This is a disease particularly prevalent among acts on Swinging Sixties pop tours. After they have played their one hit three times, bands on these tours invariably clang up a new number they have just written; a bit of timing which, oddly, usually coincides with an exodus to the bar. 'We really see this as a new beginning,' band members tell interviewers. 'But record companies these days just don't have the guts to go with it.'

This has happened to other, more prominent, old contenders, too. Sandie Shaw, lionised by Morrissey, the Troggs (picked up by REM), half a dozen collaborators with the Pet Shop Boys - none quite grasped that their five minutes back in the hip-light was because they were regarded as camp back-drops to the main event. All of them thought their time had come round again for good and saw record projects falter.

Lulu, who has undergone a re-invention of her career before, when she was picked up by David Bowie and took 'The Man Who Sold the World' to number one in 1970, may well be savvy to Take That's joke. She might well appreciate that just because their teen audience applauded her it doesn't mean they will rush out and buy an album of her singing new songs to a rave beat.

But if she doesn't, she could learn from the experience of Rolf Harris. Last year, Rolf was lauded for his version of Led Zeppelin's 'Stairway to Heaven'. Rightly, it was a killer. 'Ripe with grooves and hot with attitude. It was, if you will, musical cubism,' read the sleeve notes, so arch they were circular.

The charm of the gag was its lack of self-consciousness. Rolf had never heard the song before, knew not of its notoriety, was completely unaware that whole departments in mid-Western universities have spent years researching its supposed Satanic undertow. He had simply done his version because he was asked to by an Australian television show. Which in the process scored a double irony whammy, sending up at the same time both Sir Rolfred and the most pompous rock band in history. 'You think of all the times you busted a gut trying to organise a hit record,' Rolf said at the time. 'And here's something we did so casually catching on. Jeez.'

After his Stairway climbed to number nine in the British singles charts, the most vertiginous position radio's most- requested song of all time had ever occupied, Rolf thought he spotted a gap in the market. So he went ahead and recorded a whole album of rock covers: 'Satisfaction', 'Walk on the Wild Side', 'Honky Tonk Women', 'Wild Thing', 'Smoke on the Water' and 'Bad Moon Rising', the classics of the canon, all driven by the a-whoob-bloob-blimp-bloop of the wobble board. Sadly, at the time of writing, no one has taken up the chance to release it in Britain, sensing, perhaps, that the joke has worn thin.

'The album just seemed to fall between projects,' said Kaz Mercer, of Phonogram, the British record company which handled Stairway but declined the chance to take on the album. 'I'm not quite sure what happened. But it didn't'

'Rolf is actively looking for a deal at the moment,' his publicist Pat Lakesmith said. 'But as yet there are no takers. In the meantime he has got an album out of his own greatest hits, 23 tracks, from Sunrise to Stairway. It's on EMI and it's called Didgerido All That?

Now that, Danny Baker could make an entire series out of.

(Photograph omitted)