just be careful with the locking blade. I was stuck in battersea a couple months back and decided since I was in london to go on the London eye. Two of us in full flight crew uniform, full identification on us, pay to go on and wander up to the security point just in front (incidentally run by British Airways). Guy askes if either of us have knives on us (both have), he has a look at my mates - a 3.5" non locking SAK, which is fine, then has a look at my wave and declares that seeing as it has a locking blade on it, regardless of the blade length, it's illegal and that he has to confiscate it. That's even if I then turned around and decided not to go on the London eye!
Now bearing in mind I go through airport security run by the same company on an almost daily basis, get access to the aprons and flight decks of multi million pound aircraft, and have the lives of my passengers in my hands, it seems incredible that I'm then not allowed to have a small multi tool in my pocket to be suspended in a small glass bubble over central London. There we go though. You've been warned!
Now I understand they're illegal anywhere in the UK without good reason so just be careful you don't get it confiscated by police or security. They're apparently getting hot on it in train stations at the moment
