And yet he knows, in his heart, that if he buys all his food from Waitrose his wallet is going to take a real bashing. From Monday to Friday, therefore, he ekes out stews with dried beans, does imaginative things with leftovers, even eats kale. But come Saturday, BAM: he roars around Waitrose hurling anything with Heston Blumenthal’s face on it into his trolley, ending up with a whole 28-day matured forerib of beef and a nice chunk of halibut. He persuades himself that the Dine In for £10 offer is saving him money. His shop costs him £260. He tells his wife it was £62.48, which is what the beef cost. As he would notice, if he did the maths, he is caught in the classic trap of the yo-yo dieter: he spends more in Waitrose each week as a result of his austerity scheme than he did before.