Atomic Kitten may look like hair-and-beauty-salon workers, but the three girls from Liverpool - Liz McClarnon, Jenny Frost and Natasha Hamilton - are the UK's biggest girl band, having sold 5.2 million singles and three million albums since they formed, in 1999.
Ladies Night, their new, third album, features the Kittens' version of Kool & The Gang's disco classic of the same name, which is likely to contest the Christmas No 1 single slot with the straggly-haired rockers The Darkness - a case of beauty vs the beast. For now, the romantic, soulful pop of the current single, "If You Come to Me", has entered the chart at No 3.
Today, just two Kittens, McClarnon and Frost, turn up for the interview. Hamilton, who has recently been looking disconcertingly thin and signed off work two weeks ago with flu, is not present. According to Atomic Kitten's people, she has just been diagnosed with postnatal depression, 15 months after the birth of her son, Josh.
Atomic Kitten's lives are well publicised, as their weighty press-cuttings book testifies: it resembles nothing as much as the Argos catalogue. It reveals that Hamilton has gone public about her recent boob job. "Never say 'never'," Frost says. Frost has arrived for the interview wearing a Zara deerstalker and YSL-belted, low-waisted Diesel jeans, with black lacy knickers showing at the back.
The ringtone on Frost's phone, it soon transpires, is Beyoncé's "Crazy in Love". "That's how I tell it's my boyfriend calling," she confides. "But if either of the other girls phones, the ringtone is 'Sweet Dreams' by Annie Lennox."
There is something refreshingly honest about the band. Musically, Atomic Kitten may often amount to little more than an embellished karaoke act, but you get the feeling that they never intended to be anything else. While similar manufactured pop bands change their musical style as often as the weather, Atomic Kitten remain themselves. And while the Sugababes, arch-rivals with whom Atomic Kitten are often in dispute, try very hard to be cool, the Kittens - who were recently photographed for Heat magazine in a cat basket - content themselves with making good old-fashioned, no-frills pop music. Perhaps blandness is less of a risk than trying to market themselves with any edge.
"We work bloody hard, though," says McClarnon, who is wearing a black polo-neck and black Joseph trousers with a pair of office-worker glasses. She has a headache: "My mum bought me an electric blanket," she says, "and last night it dehydrated my brain." (Frost, looking on the bright side, notes: "You'll be half a stone lighter now.")
It has not always been an easy ride since they were brought together by Andy McCluskey, formerly of Orchestral Manoeuvres in the Dark. In 2001, one of the founder members, Kerry Katona, announced her departure to have a baby with Brian McFaden of Westlife. At about the same time, the band's record comapany, Innocent, lost faith in them. But then Frost, formerly of the girl band Precious, was recruited, and, in a last-ditch effort, the band released "Whole Again". It went straight to No 1, selling a million copies. Atomic Kitten haven't looked back since.
When asked the secret of their longevity, Frost doesn't hesitate. "People can relate to us," she says. "They look at us and say, if they can do it, anybody can do it."
'Ladies Night' is out now on Innocent/Virgin