Is Brexit uncertainty affecting the high street?

Christmas on the high street has been very much a case of winner takes it all. Sainsbury’s today, like other big supermarkets, reported a rise in sales. Cash-strapped consumers seem to have spent what money they do have on food and drink. But some of the general retailers have seen a big drop in spending. Could this, as some say, be down to Brexit uncertainty? Or is there a more fundamental shift in shopping habits?