However, in a move aimed at protecting investors' funds, the company intends to offer a limited "guarantee" against stock market falls. BZW, which has been chosen as fund manager, will buy shares tracking the FT- SE 100 stock market index. Income that would normally accrue to the fund will be used to buy options to help protect against market falls.
Rober Colvill, managing director of Marks & Spencer Financial Services, said: "We cannot offer an absolute guarantee, but we can protect against the risk of a more serious market fall happening, such as the October 1987 crash."
The company will also offer a range of financial products by mail order, including critical illness and family protection plans. Potential buyers will be able to pick up product brochures from any of the company's stores and call a free-phone number linking them to a centre in Chester.
Trained staff will answer any technical query over the phone but will not push these products to clients. They will be sold on an execution- only basis.
Geoff Lister, chief executive at Bradford & Bingley, which gives independent advice to clients, criticised the scheme. "We think the execution-only service for pensions is dangerous from a customer's point of view. People need advice on such important decisions."
If clients buy an M&S pension or another product, the company says it will give them a 30-day money-back guarantee period, more than double the time normally offered by firms.
M&S clearly aims to capitalise on its name and reputation - and on the relative aversion to risk of millions who already shop in its stores. Keith Oates, chairman of financial services arm, said: "Our aim in designing these products has been to provide life assurance and pensions plans which reflect the M&S traditions of quality, value and service."
The link between a strong brand name and the offer of new financial products is not new to Marks & Spencer.
It already has 3.4 million charge accounts, while 350,000 customers have borrowed almost £900m in personal loans.
M&S launched two unit trusts in 1988 and now has funds under management of almost £300m.