Agony Aunt - Katie Exton

Corkage in UK restaurants often seems to be a bit of a contentious issue. Managed well, I think offering it can be a great service, of benefit to both customer and restaurant. Obviously the biggest argument against is the fact that the corkage charge will be less than the profit you might make on higher-end wines. One could also argue that, when larger groups bring several expensive old wines, the time and attention required outweighs the return. And, in a worst-case scenario, there could be an excess of people BYOing mediocre wines and nobody buying off the list. But I think this would only happen if your corkage fee was incorrectly priced and the service overly advertised.

There are also benefits. In my experience, most customers BYOing offer the sommelier a generous taste, which helps to compensate for at least some of the potential financial loss. Furthermore, customers will come to your restaurant because it allows BYO - the fact that they can enjoy a special bottle with good food and have it served correctly is, quite rightly, seen as a not inconsiderable benefit.

The key to it all is to get the corkage fee right. It needs to be high enough to put off people bringing any old bottle, but still reasonable. In addition, I have found that most BYOing customers buy a bottle from the list as well. A more cautious policy, where corkage is higher, but reduced when something is also chosen from the list could also be successful.

Most importantly, remember that your corkage fee is 100% profit, so if the price is right it should give you a better return than your entry-level wines. The restaurant makes money, the sommelier gets to taste amazing wines that aren't on the list and the customer is happy - an excellent result all round.

Katie Exton, sommelier at Wandsworth's Michelin-starred Chez Bruce.

• Sommeliers