One common factoid trotted out by business journalists is that Tesco takes one pound of eight pounds the British public earn. This is usually a prelude to calling for Tesco to be restricted in some way so that 'local' shops may survive. This springs from a romantic view of the past where everyone supposedly knew one another.
Tesco is a reptile- it will devour all that is in its path and cares for nothing but the bottom line. Nevertheless it serves a purpose and reduces the cost of food relentlessly.
One central plank of their marketing is the Clubcard loyalty programme. This is a worldwide scheme now and it is possible to earn points in Thailand and spend them in London (I am told). Tesco knows more about its customers than any other retailer and can sometimes appear psycic. I have on occasion been walking down the street and decided that I needed a particular brand of ice cream or shoelaces. Upon entering the shop I find these exact products adjacent to one another. How did they guess I would want these things? They cross reference their Clubcard data with every other piece of research ever done and know our preferences better than we do.
The scheme is too sophisticated to be gamed in the way that others may be. The only way to come out on top is to exchange food vouchers for leisure experiences. This triples the cash value. The reasoning seems to be that a �5.00 shopping voucher reduces your spend in Tesco while a 'free' day out does not.
Join the Christmass club scheme while you are about it. This saves up all of your vouchers until November. If you choose to add some cash to the account you will be rewarded with extra vouchers in addition to the ones earned by shopping.