M&S is expected to deliver like-for-like sales growth of up to 3 per cent - but in recent days a number of major banks, including Morgan Stanley and Credit Suisse, have cut their forecasts with some fearing like-for-like sales may have fallen. Some analysts even believe that pre-tax profits may now not reach the symbolic £1bn mark this financial year.

"It might be touch and go whether they pass the £1bn barrier after all," said Nick Bubb, retail analyst at Pali International. Another leading analyst said: "I'm below consensus at the moment but I wouldn't be surprised if I had to bring the numbers back a bit more."

City traders warn that a disappointing update from M&S could trigger further share price falls. Short sellers have staked hundreds of millions of pounds on further falls. Data Explorers believes that the two most shorted stocks in the FTSE 250 are HMV and Debenhams.