Speculation is rife that UK high street favourite Marks & Spencer is facing problems of a previously underestimated depth, following the revelation, through the Competition Commission's supermarket report, that profits from the retailers' food division have plunged.The news will shock investors, as M&S normally refuses to publish returns and it was consistently assumed that, financially, the upmarket food business was the store's saving grace. That is simply not the case, however. From a five-year peak in 1996 of £247m, operating profits during 1999 fell to just £137m, despite an 8% increase in sales to £2.8bn.