I just bought Tesco, but be careful on this one.
The main reason why Tesco struggled in this half is down to the new CEO. Basically, Tesco have a rewards system where you get 1p back for every £1 that you spend. When Britain went into recession last year, they doubled the rewards, giving customers 2p back for every £1 they spent. However, last year they went back to giving 1p back for every £1 spent, and then used the savings to market a new price drop campaign called "The Big Price Drop". This ended in a fiasco, as it turned out that Tesco merely increased prices in the week before, only to drop them back to the original price. The old CEO (Sir Terry Leahy) had been in charge since 1997 was an experienced (and visionary) retailer and would have known better to try and con customers like that.