Anthony Rose: The main reason BYO isn't bigger is because it undermines the gross profit margin

One of the best meals of my life was at Tetsuya's, a restaurant reached through a hole in the wall in a Sydney suburb, where you could bring your own bottle, free of charge. Having raided their cellars, my hosts handed their bottles to the waiter and the wines were served as unsnootily as if thoughtfully selected by the restaurant itself. Occasionally you come across attempts to replicate the Antipodean BYO culture here. Hullaballoos was a BYO chain, but it sold up, leaving a sole survivor to represent the culture, The Muset in Clifton, Bristol.

BYO is a sub-culture in this country, tolerated rather than encouraged, but you might be surprised at the number around. I'm a fan of some of the south-west London places listed on Tom Cannavan's website (wine-pages.com/food/byoblist), among them, Amaranth Thai Market in Earlsfield, Mirch Masala in Tooting and Miraggio at Fulham Broadway. Don't expect Michelin-starred cooking. As an opportunity to take a few nice bottles, though, and come away with a full stomach and a light bill in equally satisfying measures, it's a great way to eat out on a budget.

The main reason BYO isn't bigger is because it undermines the gross profit margin that most restaurants apply to their wines. Between 60 per cent and 75 per cent is standard. That's two-and-a-half to four times what the wine cost the restaurant. The fact is that the wine list essentially subsidises everything else. "The costs of the kitchen are higher, so the profit contributions on non-food items such as spirits, water, coffee and wine are higher," says Nigel Platts-Martin, one of London's top restaurant wine buyers. If you accept that as the inevitable quid pro quo of enjoying a good meal out, it only becomes a rip-off when the restaurant ends up greedier than the customer.

Roger Jones, of the award-winning restaurant The Harrow at Little Bedwyn, Wiltshire, is keen to encourage custom without offering lunch for £10 – "the route to failure", as he puts it. "The car showrooms on Park Lane have not replaced Aston Martins with Ford Mondeos," he says. Instead, he is offering free corkage to guests opting for his Gourmet Tasting Menu on a Wednesday, Thursday or Friday lunch or dinner.

No doubt restaurants could do more to bring customers in with better deals on wine, such as free or minimal corkage, a free glass, or a discount on wines on quiet days. Corkage is still one of the best-kept secrets of the wine trade. At a Carluccio's recently, I accidentally discovered that you can order one of the superior bottles in their retail front-of-house to have with your meal for just an extra £5. It's policy, but the MD told me, "it's one of our hidden glories – until now". The Tate's publicity for its £3 for a glass of wine or £5 for two at lunch is the exception that proves the rule.

Many top restaurants will discreetly offer corkage of £10 to £20 as an incentive to loyal customers wanting to bring in a special bottle, but the uptake is surprisingly small. When one top London eatery hooked up with a fine wine merchant to offer £10 corkage to its deep-cellared clientèle in January, the uptake was so minimal as to be barely worth the effort. "Nominal corkage tampers with the business model, which is dangerous," says Platts-Martin. "I don't want the whole world bringing in a bottle of muscadet to save money." Save your muscadet for picnics then and keep your Château Latour for drinking free, apart from the purchase price, of course.