THE picture could be one of a million nursing homes. The elderly residents are busy watching television and hardly seem to notice the special visitor who has entered the room.

"Tea's up," trills the diminutive pop star Geri Halliwell as she carries in a tray of refreshments. And so Labour's first election broadcast of the campaign continues to the party's upbeat soundtrack of Lifted by the Lighthouse Family.

Ms Halliwell, who once famously said that Margaret Thatcher was the original Spice Girl, has swapped allegiance to Labour after declaring she "genuinely believes in Tony Blair".

The broadcast, entitled The Work Goes On, lists what Labour says it has achieved since coming to power in 1997, over a succession of pictures featuring nurses, families and other images of life in Britain.

The pop star believes Tony Blair has "done a lot of good work in the last four years".

"A lot of people knock Britain but I have to say I'm proud of this country, and the opportunities it offers people," she says. "Cherie and I have worked together for Breast Cancer Care and I think she's also fantastic, a great role model. We all need good parenting with love and guidance, and I think Tony and Cherie are great examples to us. That's why I agreed to be involved in this election broadcast."

But it was a different story back in 1996 when the Spice Girls proudly announced they were backing the Conservative Party.

In an interview with The Spectator, Halliwell said: "We Spice Girls are true Thatcherites. Thatcher was the first Spice Girl, the pioneer of our ideology - Girl Power."

She even went on to air her suspicions about the opposition leader - a man who had never done any proper work. "The real problem with Blair is that he's never had a real job. In the olden days a politician could be a coal miner who came to power with ideals," said Halliwell. "Not Blair. He is just a good marketing man."

The multi-millionaire, currently at No 10 with her remake of It's Raining Men, is not alone in her gushing support of Labour. Other celebrities featured in the election broadcast include test cricket umpire Dickie Bird and paralympic gold medalist Tanni Grey-Thompson.

Past Labour supporters have tended towards the trendy pop set in the form of Simply Red's Mick Hucknall, Noel Gallagher and Pete Cunnah of D:Ream. Tony Blair even hosted a party at No 10 for celebrities in 1997. Old Labour supporters have also famously included Paul Weller and Billy Bragg.

The Conservatives on the other hand have chosen Wombles frontman Mike Batt to pen the Conservative election campaign music. The party has traditionally shunned the lightweight celebrity in favour of stalwarts Cilla Black, Jimmy Tarbuck, Patti Boulaye and Phil Collins.

But with Halliwell's youthful endorsement, can Labour expect to see thousands of teenagers rushing to cast their first precious vote on June 7?

The signs are it won't. Heather Clarke, 18, who is studying English at Durham University says: "I don't think using celebrities will make any difference. I wouldn't be swayed by some pop star advertising a political party."

Sociology student Emma Roe, 18, says: "It's good because it sparks an interest in politics for the younger generation, but it's very false and a bit pretentious. People like Geri Halliwell have nothing at all to do with politics and probably don't even care about it."

Dr Joan Harvey, a psychologist at Newcastle University, agrees the move won't gain young voters. "It's a gimmick to gain extra publicity and it's worked because everyone's talking about it. The fact she's technically changed her allegiance has actually added to the publicity. It's quite a clever move. But it's weeks before the election so the effect on voters will be nil.

"I think we also have to remember that the Spice Girls were popular with the 11 to 14-year-olds and they are not the ones who are going to be voting."

But Dr Harvey warns Labour's publicity campaign could backfire if it continues using "superficial" celebrities. Halliwell has already admitted: "I don't know a lot about politics, but I have a great trust in him as a leader."

Says Dr Harvey: "If they over do it with a string of celebrities they might start looking very gimmicky and they could end up with a lightweight branding. That will be dangerous for them because it is liable to turn voters off."

Colin Larkin, editor of The Encyclopaedia of Pop And Music agrees Halliwell's support of Labour could have the reverse effect. "Geri has desperately been doing loads of things which will make her loved by people," he says. "I'm not too sure whether her support will help Labour. In fact, it could have the reverse effect and prove incredibly damaging. She might appeal to the under tens but they will not be turning out in force to cast votes on election day."

John McKie, editor of Q music magazine says: "You could be cynical and say Geri is doing it for the publicity. But Frank Sinatra used to chop and change from Democrat to Republican with alarming frequency and I think we could see Geri switch back to the Conservatives again."

Experts believe celebrities have different reasons for getting involved in politics. Larkin says: "In some cases you do get celebrities who are showing their hearts by getting involved. I do believe Billy Bragg, Paul Weller and UB40 came out in support of Labour for genuine reasons.

"But others just see it as another method of self-promotion. At election time I think it is irrelevant what these people think. Some are genuine, some are not - the jury is still out on Geri."

McKie adds: "Celebrities just seem to love politicians - maybe it is because that these days they are the ones wearing the better suits. I think a lot of today's pop stars love Tony Blair because, during the Clinton administration, he won over America. Most of today's British pop stars would love to be able to do the same.

"Celebrities just love the idea of glamour and in the world of politics you don't get anybody more glamorous than Tony Blair. He wears designer suits and takes holidays in Tuscany.

Another thing which might appear attractive is having Alastair Campbell doing your PR. He has done a great job of getting Labour splashed across the front pages and I'm sure many celebrities would love that to happen to them."

For Halliwell, who was busy promoting her new album the day after the election broadcast, it already has.