What’s the correct protocol about bringing your own wine to a restaurant?

Isn't it a bit tacky? Not necessarily. It depends on several factors, like the attitude of the restaurateur, your own budget and the kind of wine you intend to bring to the table.

If the restaurant has a good wine list that has been carefully selected to complement the style of food they serve, you may be advised to accept their offerings, if you can afford them. It would certainly be a bit tacky to arrive at a good restaurant clutching a bottle of R20 plonk. But if you have a special bottle of good wine you’d like to share with your dining companion, it should present no problem, even if there’s a heavy corkage charge. Some restaurants charge ridiculously high prices for their wines, and here it is often worth bringing your own, if they allow it. In any case, it’s wise to call ahead and find out what the restaurant’s policy is regarding BYO.