Brandes Investment Partners, the biggest shareholder in Marks & Spencer Plc, has significantly upped its stake in the struggling retailer.

The fund manager now controls 15.3 per cent of the company's shares, compared to the 11.7 per cent stake it held in July.

M&S on Monday began the biggest share buyback in British corporate history as it announced it was to repurchase 27.9 per cent of its shares and return £2.3 billion to shareholders.