The Great British Bake Off is back and with it cake-based controversy. As Prue Leith announced that the technical challenge was going to be making malt loaf, that treacly, squidgy tea-time staple, she added, “Those of you who are under 35 may never have heard of it.” What? Not heard of malt loaf? Slices of damp, sticky Soreen were a staple of my childhood. My children – now students – had slices in their lunch boxes, or for tea, warmed to accentuate that fudgy chewiness and dripping with butter.