Man banned from shop after his card was declined

That manager needs a good slap. How could he not realise it was rubbish? No one walks in on their own to do that much shopping. Even with 3 or 4 trollies laden with booze you'd be getting suspicious but 22 WTF?

I think this is a breach of contract, but even without such a breach of contract, the store is legally entitled to do so on grounds of the man being an annoyance.

In fact, wasn't there a case under (UK) case law whereby a man who sat down in a restaurant, and then decided not to order anything, was successfully sued for breach of contract?

A restaurant can also sue for breach of contract if a customer makes a booking, and later decides not to show up.

The one hole in your story is that your sidebar profile says you still live in a small flat in the city.

anyway, the thing about the contract beginning when you sit down in a restaurant is true

http://www.channel4.com/4food/features/can-you-pay-for-dinner-by-washing-pots-09-02-19

The contract takes place when you walk into the restaurant without a reservation and sit down or when you make a reservation on the phone.

However I seem to remember that this only applies if the restaurant has a menu on the window or somewhere other than on the table menus.