My sister is 26 and had her driving licence with her, but my friend who is 29, does not drive – and for some reason does not carry her passport with her when she goes shopping.

So we were told we could not buy the booze.

My problem is not so much the lack of common sense shown by the woman who served us, as the supermarket's assumptions.

The reason we could not be sold the alcohol, I was told, was because the supermarket had to 'assume' that anyone with the person buying the alcohol is going to drink it.

Now since when did it become the responsibility of Tesco to assume what we do with its products when we have bought them?

What if a mother came in with her teenage daughter to buy wine to go with dinner?

Would she be refused in case her teenager downed the lot before it got to the dinner table?

It would be interesting to know why it is any of Tesco's business what people do with what they buy from the shop.

Of course, the problem would have been solved if supermarkets did not have to make assumptions and we all had identity cards.

Perhaps if we had identity chips inserted into our skin we could just be scanned at the same time as our shopping.

What are we waiting for?