They call it the "Parky Effect". Forget about obtaining blanket airplay for your band on every radio station on the dial or bribing illiterates in newspapers and magazines to pen rave reviews of your new album. Instead, send your CDs to Michael Parkinson.

The veteran broadcaster doesn't just have the golden touch when it comes to soft-soaping celebs and movie stars (though Meg Ryan would disagree); he's also credited with being a bit of a music biz talent scout.

The statistics don't lie. Getting the nod to perform on Parkinson's chat show has done wonders for Jamie Cullum, Norah Jones, Michael Buble, Will Young and a host of other middle-of-the-road acts. Virtually unknown when they initially appeared on Parkinson, they saw their sales and profiles rise considerably in the wake of the show thanks to the Parky Effect.

For example, in the two weeks after her performance on the show, sales of Diana Krall's A Night in Paris album shot up by 5,088 per cent. That's right, five thousand and eighty-eight per cent. No wonder every single record company TV plugger is loitering with intent outside the Parkinson production office, begging those inside to put his or her act on the show.

Of course, there are other TV chat shows which can give acts a sales boost similar to Parkinson. Getting a band on The Late, Late Show earns Irish publicists a gold medal and a round of applause, while there is always considerable interest in the musical acts chosen by Jonathan Ross.

Yet Parkinson remains the big chief of TV chat-show presenters, his transfer from the BBC to ITV certainly not lessening his appeal (5.7 million viewers tuned into the first show of the new series). But will the Parky Effect still apply in the coming months now that the show has changed its booking policy?

ITV wants to give the show "a younger, funkier edge" and, before the mind begins to boggle at the thought of Parkinson introducing the Aphex Twin or Autechre alongside Ronan Keating or Sting, this new policy probably means more acts like Razorlight. Parky saw footage of the band playing at Glastonbury and wanted them for the first show of the new series. What the audience made of Jonny Borrell and Razorlight remains to be seen, and we are sure the bean- counters at Universal will be monitoring sales carefully in the coming weeks to gauge the Parky Effect.

While TV exposure does not break a band in itself, it's an important part of the promotional combination which helps to build a profile and push sales.

The BBC Radio 2 effect is seen as almost as important as the fillip which goes with a Parkin- son appearance, now that the Beeb's once doddery music station has reinvented itself as the place where the 50 quid man goes to check out what he should be buying. The death of the music press went hand-in-hand with increased music coverage in national newspapers and a none-too-subtle shift in what is covered.

Such changes now mean that the musical range of what is covered is getting narrower and narrower. No matter how "funky" or "edgy" ITV wants Parkinson to be, it will not extend beyond Scissor Sisters or maybe Franz Ferdinand. The guitar acts who appear will be sanitised in every way because the show doesn't want its audience spilling their tea in shock or, worse, switching over to the Beeb. You can expect the new acts which the show will feature to be along the lines of "the new Norah Jones" Gwyneth Herbert, classical girl-band Wild or the now singing and song- writing Minnie Driver. Nothing to rock the safe, steady rhythm of the Parkinson boat. Inevitably, this will have a knock-on effect on what is signed and released.

At the moment, record company marketing meetings are where frantic, panic-stricken people despair at how hard it is to get coverage for their acts. There's one way around: let Michael Parkinson and his ilk decide who and what gets a major label release in the first place.