Last month M&S said Steve Rowe, the current head of its general merchandise business, would succeed Marc Bolland as chief executive in April. Rowe's biggest task is to revive clothing, which saw a slump in sales over Christmas.

The 132-year-old high street stalwart said on Thursday the new 31-piece womenswear collection, which will launch in April, was curated and handpicked by Chung and is focussed on bringing back to life items from the group's extensive archive.

It said the project is the first of the retailer's ‘M&S &’ series, a sequence of collaborations with designers, brands and fashion icons.

Last year a 199-pound seventies-style brown suede M&S skirt was a massive hit after it was lauded by Vogue magazine and worn by Chung, selling 4,500 in the six weeks after launch.

"It's an ideal and clever pairing. Alexa is an avid supporter of British fashion and nothing is more so than M&S, so she'll make for a great contemporary ambassador as well," said Jessica Bumpus, a freelance fashion journalist who has worked for Vogue, The Wall St Journal and The New York Times.

Shares in M&S, down 23 percent over the last three months, were up 1.9 percent at 417.3 pence at 1128 GMT.

(Reporting by James Davey and Limei Hoang; Editing by Greg Mahlich)