Re: Flaw in the argument
Moultoneer: "for example on Tesco's on-line store 1KG of McCains oven chips are £1.75 yet 2.5KG of baking potatoes are £2"
You are comparing prepared branded and non-prepared non-branded goods. A better comparison would be Tesco's EveryDay Value chips 82p for 1.5kg.
By the time you have washed your bakers, peeled them and chipped them your £2 of potatoes is 1.5-2 kg of chips. And you have spent 30 mins of your time for free. Then you have to cost your oil (and you need a lot to fry that many chips). Starting to look like 4-6 times more expensive, isn't it?