David Norgrove, who Marks and Spencer said would step down from the company's board of directors "in due course", has paid the price for a tough festive season by the group seen as a bellwether of the British high street.
In the seven weeks to January 10, overall sales fell 0.1%, with the drop expanding to 2.3% when like-for-like sales were taken into account.
Clothing was the biggest loser, dropping 3.0% in actual terms, with Marks and Spencer admitting that some of its ranges were simply not up to standard.
"The fall in clothing sales was driven by a weak performance in certain key womenswear areas, notably knitwear, coats and suits, where our ranges were not strong enough and the warm weather had significant impact," chief executive Roger Holmes said in a statement.
Growth in food sales, which was up 4.7% overall but only 0.5% higher in like-for-like terms, was also "disappointing", Holmes added.
The sales figures are a blow to one of the most venerable names in British shopping, which has turned itself around from one of the most difficult period in its 120-year history.
Marks and Spencer hit big trouble several years ago as poor strategy and a dowdy, out-of-date image badly dented profits.
However sweeping changes, including the sale of many of its overseas stores and initiatives such as specialised food-only outlets, brought about a strong recovery.
Much of the turnaround has been down to Belgian-born Luc Vandevelde, who was appointed chairperson in February 2000 with the intended mission of pulling the company out of the doldrums.