Retail is detail. That means it's all about attracting people into the shop, ensuring that they are served politely with the products they want at a price they find affordable, so they come back again, and again.

In the case of Tesco, it means inviting people into the store on the basis that they can buy a product advertised at a cut price, even though Tesco knows that the advertised product may not always be available.

This is one of the pitfalls of operating giant superstores with thousands of lines distributed through complex channels. An independent retailer can choose to tear down a poster advertising a slashed price once the product has sold out at that price.

So how does Tesco, a business to which millions of people are intensely loyal, handle the disappointment of those shoppers who go to the store and find the cut-price product is not on the shelf?

This is how. On a notice board they find 'Answers to frequently asked questions'. One of these - which shows just how many disappointed customers trundle to the store only to be let down - is: 'What do I do if I can't find a product advertised at a promotional price?'

The answer is quite cute: "Please inform customer service and they will give you a voucher which will entitle you to the same product at the advertised cut price on your next visit to the store."

So Tesco can turn a problem into a new selling opportunity, believing that the customer will return (highly likely) and that the product will be on display at a higher price (also highly likely).

This is hard-nosed retail thinking. Once a shopper has crossed the threshold of your store there is always the risk she may be disappointed. But do not let this affect your footfall frequency. Like Tesco, think of creative ways to limit the damage.