The fourth paragraph in their Terms and Conditions, which presumably there is a check box agreeing to at checkout, is as follows:The comments on that article expressing unforgiving outrage that Tesco should bite the bullet on this bit of human error and honor their "contractual agreement" are pretty funny.
That seems very clear. Tesco have covered themselves for exactly this eventuality.If, by mistake, we have under priced an item, we will not be liable to supply that item to you at the stated price, provided that we notify you before we despatch the item to you. In those circumstances, we will notify the correct price to you so you can decide whether or not you wish to order the item at that price. If you decide not to order the item, we will give you a full refund on any amount already paid for that item in accordance with our refund policy in section 7 below.