Despite the success of their 1996 album, "Alisha Rules the World", which spawned four Top 20 singles and a Brit nomination, the duo has made what Shellie calls "a conscious effort to be more about music and less about the angles. We worked so hard for two years, putting all that slap on. We said we wanted to look really way out, but when the two years were up, I didn't want another bit of make-up on me."
Despite the fact that their lyrics neatly and cleverly address the worries of twentysomething girls, their fan club is 70 per cent male, but the suggestion that they're quirky pin-ups is briskly dismissed. "It's not because they fancy us!" snorts Shellie. "We don't get romantic letters"
Their new album, "Illumina", sounds like a breezy folk-pop take on "Bridget Jones' Diary", with lyrics that fret about partners being 'karmically close' or girlfriends with irksomely perfect style. But darker concerns lurk behind the chirpy tone.
Shellie suffers quite seriously from compulsive disorders - though she feels her condition is improving. "I don't do the cleanliness one any more", she says. "I used to wash my hands until they were cracked and dry". As she speaks she takes a cloth pouch, full of small, polished stones, from her handbag. "This is my lucky bag of pebbles. I have to have these everywhere I go, otherwise I completely lose it."
Karen sighs. The pair used to share a flat, until the pressure or working and living together proved too much. "Shellie, just put them away", she says. Undaunted, Shellie removes another. This one is blue. "I have to carry this. It's an eye. It watches over me. When I leave the house I have to kiss the door four times. Now I live on my own I can just get on with it."
From Bjork to Meredith Brooks, the charts are full of female singer-songwriters with a side order of intriguing kookiness. Yet in many ways Alisha's Attic defy their self-consciously poppy image. In the summer they were part of the campaigning, all-female Lilith Fair tour in America, alongside earnest femme-rockers such as organisers Sarah McLachlan and Natalie Merchant. The tour, which had a one-off concert in London this week, was attacked in some quarters for being overly political but the sisters take a typically down to earth view. "It was brilliant" says Karen. "It was a bit girlie-together, a bit wimpy-hippy" adds Shellie. "They asked if we'd speak at the press conference, but we just wanted to play our music, not discuss women's problems. We thought it was just a celebration of women in music."
Music is important to them. The sisters say their own role in their success has been downplayed. Former Eurythmic Dave Stewart, famed for working with strong female artists such as Annie Lennox and proto-Alisha's Attic Shakespear's Sister, is painted as a lurking Svengali figure. Yet, although he produced the whole of "Alisha Rules The World", he was responsible for just two tracks on the noticeably less upbeat "Illumina" (released on Mercury on October 5).
"We were going for ten years before we met him", says Shellie. "We still enjoy working together and we'll probably work together in the future, but we've moved on."
Karen once said they were "normal girls from Dagenham until we started this pop thing and now we're all wonky". She explodes into laughter when reminded of the quote. "You have to do bizarre things to sell records". "But", adds Shellie with a smile, "we were never really normal".