Can Cassani work the same magic on M&S as she did on Go?

Ms Cassani will join the firm on 1 October as non-executive director, the retailer said.

M&S chairman Luc Vandevelde said he was "delighted" with the appointment.

"[Barbara] has an impressive track record in one of the toughest industries in the world, with experience of both start-up and established businesses," he said.

'New ideas'

Ms Cassani - last year's winner of the Veuve Clicquot Businesswoman of the year - is currently chairman of London 2012, which is bidding to bring the Olympics to the capital.

The American said of her new job: "I look forward to encouraging new ideas that will strengthen connections with the customers."

Previously, her career included a spell in British Airways' sales department from which she was appointed in 1997 to run the no-frills airline Go.

Three years after its formation Ms Cassani led a �110m management buyout of Go from BA.

The airline was sold to Easyjet last year for �374m, netting her a reported �16m.