The figures mean Waitrose is fastest growing supermarket chain in Britain and come as Ocado – the online grocer that delivers Waitrose products – set a new record for the number of deliveries in a single day, of 17,500.
New M&S chief executive Marc Bolland, who arrives from Morrisons in May on a £15m first year package, has the task of making up ground on its rival.
M&S reported a 2.6 per cent rise in its third quarter results.
Meanwhile Waitrose has been boosted by its low cost Essentials range.
John Lewis, which owns Waitrose, also reported sales up 15.6 per cent in the week to the 30 January.