Marks and Spencer's first-half results paint a picture of a company divided. One the one hand, its food business is performing well, with rising like-for-like sales and improved profit margins. On the other, general merchandise continues to struggle, booking lacklustre sales and lower margins. With a swathe of plans to accelerate food growth, that side of the business looks ship-shape. However, a question mark hangs over whether its non-food performance is turning a corner. Katy Askew reports.