Marks & Spencers, the high-street clothing and food retailer, has this morning reported a 1.5% increase in food like-for-like sales. In an interim statement for its first quarter of its 2010/2011 financial year it said group sales had increased by 4.4% and food sales were up by 2.9%. The group said its improved food like-for-like sales were due to a “continued return to quality” and “innovation”.