John Lewis is to launch its biggest fashion ad campaign to date, featuring supermodel Karen Elson.

The department store group has invested£1.5 million in the campaign, which will launch on September 15 to coincide with London Fashion Week.

The campaign forms part of John Lewis Partnership’s multimillion-pound investment in its fashion offer, which represents£600 million of John Lewis’ turnover.

The campaign, which features rock chick Elson – who is married to White Stripes frontman Jack White – will appear on billboards, in stores and in glossy magazines, including Vogue.

The redhead was one of the iconic models of the 1990s and has featured in campaigns for Yves Saint Laurent, Louis Vuitton, Versace, Christian Dior and Chanel.

John Lewis has also cast male model James Penfold, who has fronted campaigns for Armani, Dunhill and Missoni, as the face of its menswear campaign.

Next week, John Lewis will unveil its interim results for the six months to July 26. Overall fashion sales have risen 5 per cent. Sales of own-brand womenswear soared 31 per cent, compared with two years ago and sales of men’s brands have rocketed 38 per cent.

John Lewis head of brand communications Craig Inglis said: “Major new brands have come into our shops over the past year including Day Birger et Mikkelsen, Jaeger London, BCBG, Whistles and Reiss.

“We felt the time is now right to invest in a major fashion ad campaign to let shoppers know – many of whom already shop with us for beauty or home products – that, whether you are 20 or 60, we have a superb fashion collection featuring many of the best designer and high street brands around.”