BYOB is a tricky subject in my view. I've had some great flights, and great conversations, aided by a little booze taken from the duty free (an example that springs to mind is a couple of supremely cool Russian experimental physicists on a Baku-Tbilisi flight, where they explained their experiments as we shared a small bottle of Jägermeister) but, unfortunately, when it turns to Britain it always descends into chaos. I think I've written about it here, but I've come to the conclusion that duty free alcohol should either be banned or packaged in some way not to be openable, when flying out of Britain, after inspecting a 747 that had just arrived from Vegas. Parts of Club and Traveller were soaked in vomit, blood, some strange liquids and Doors 3 smelt of rancid urine (because somebody couldn't wait for the loo, apparently). The police had to arrest three people. And that's unfortunately quite common on routes such as LAS and a lot of Spain.