In an interview in the Mail on Sunday newspaper, Sir Stuart Hampson said that he could not agree to breaking up the John Lewis trust, set up in 1924 to ensure the company was run as a cooperative.

"I cannot agree to any question that envisages breaking up our trust status," he said.

Mr Hampson has come under increasing pressure to put the matter to a vote, following the conversion of other mutual societies like buiding societies and the Automobile Assocation.

The matter is likely to be discussed at the retailing group's council on September 20, at which representatives from the 25 department stores and 118 Waitrose supermarkets will be present.

Plans for a debate on a stock market floatation are backed by Peter Fineman of Peter Jones, the group's flagship department store in Sloane Square, London.

But Mr Hampson as chairman of the Trust controls 60% of the votes, effectively allowing him to block any move to take the group public.

Cooperative philosophy

The 40,000 employees, called partners, currently enjoy a share of the company's profits and subsidised benefits ranging from theatre tickets to holidays.

Mr Hampson admitted that as the retailer had grown, so it had employed more people who were not in favour of its cooperative principles.

"It is inevitable that the bigger our business becomes, more people will join who are not attached to Spedan Lewis's principles," he added.

The group had profits of £237m on sales of £3.5bn in 1998.

It was founded in l864 when John Lewis opened a drapers' shop in Oxford Street. It was his son, John Spedan Lewis, who first began the experiment with employee ownership in the early part of this century.