The laws are a bit strange in the UK. Some weapons are illegal, telescoping batons, autos, gravity knives, ballisong, shuriken, and a few others. They are illegal to carry, buy, sell, lend, import, export etc. If you already have one at home thats actually ok it just cant ever leave there!

A sub 3" non locking folder you can carry without an excuse. If the police ask for one you just tell them its a sub 3" non locking folder and you dont need one. However you still cant carry one of those in a school or court or airport. The only other exceptions are when the knife is part of your national dress (Scotsmans Dirk and Sgian Dubh) or religion (Sikhs Kirpan).

Everything else you can carry as long as you have a reasonable excuse (self-defence doesnt count though). Whether the excuse is reasonable or not is up to the courts. So if you need a knife at work and feel a locking blade is safer then you could carry one reasonably at work and to and from work. The police might object to you going home via the pub though. I've carried a katana (in a bag) to a dojo - no problem there. Knives for sailing, climbing, diving, woodcraft etc. You just have to be able to justify it. I've stood and talked to a policeman and he could see I was carrying a diving knife, I was also carrying all the other stuff though so he said nothing. Note that in a city a knife will be frowned upon but you probably could take a billhook into a countryside pub for lunch and no one would bother. Its open to loads of interpretation. Technically the Leatherman wave is illegal for EDC in the UK but unless you are causing trouble you would probably just have to say its a useful tool and you would get away with it.

As to the specific question of carrying Dougs knife to the pub from home I cant think of any reasonable excuse off hand. Work to pub and had forgotten about it as its at the bottom of a pack perhaps but from home no.

Waving any blade or any other weapon is an offence in itself. And using any object is use of an offensive weapon if carried for that purpose. So baton bad walking stick ok. There is also some leeway so using a stick against person = assault, against 8 people with knives probably ok but you will be charged - its up to the court to then let you off with it.

The other thing is how likely are you to be stopped. If you look reasonable and dont cause trouble the police are unlikely to search you in the first place. If you look like a thug and act in a threatening way you could be searched and I'm affraid Doug's lovely locking knife would be removed.

There is loads more and better info available on the British Blades Forums including several serving policemen who would be willing to answer any questions if you wanted to visit the UK. Dont know how to put up a link but I have seen Chris there so he may be able to. please?