Marks & Spencer faces another damaging rift with shareholders over a decision by Sir Stuart Rose, its chief executive, to invest in a business venture founded by Martha Lane-Fox, one of the high street retailer’s non-executive directors.

The Association of British Insurers (ABI) said yesterday that the move raised fresh question marks over corporate governance standards in the M&S boardroom only weeks after the revolt over the forthcoming promotion of Sir Stuart to the controversial dual role of executive chairman.

Shareholders concerned about Sir Stuart’s grip on the boardroom in his new role were promised that M&S would consider hiring two new, independent non-executive directors.

However, the ABI questioned yesterday whether Ms Lane-Fox, co-founder of Lastminute.com, could now be seen as independent given Sir Stuart’s investment in her Lucky Voice karaoke chain.

Peter Montagnon, director of investment affairs, said: “This is another example where the company has deviated from the code and needs to provide an explanation to investors if they wish Ms Lane to remain independent.

"It is important and raises additional serious issues. The company needs to think about this very carefully and quickly before the annual meeting in July.”

According to Companies House Sir Stuart has 1.1 per cent of Lucky Voice.

An M&S spokesman last night said: “This is a private matter between M&S and the ABI.”

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