I can probably answer this one. Basically UK law is really quite strict on what you can carry as far as knives go. The only type of knife you can generally carry (i.e. as EDC) would be a non locking folding knife with a blade under 3 inches in length. The standard Swiss Army knife is the one that most commonly fits under this classification and the Champ is an damm good multi tool with a legal blade over here.

The leatherman wave, and any other locking knife regardless of length is illegal to EDC.

The way the law is worded is that it any kind of fixed blade knife is illegal unless carried for specific purposes (which I will list below), and a folding knife that locks is considered a fixed blade in the eyes of the law. Police officers work on a very simple criteria in determining if the knife is illigal. Does it lock into place? Is it over 3 inches in length? If the answer is yes to either then it is illegal to EDC.

Oh and your car is considered a public place in the eyes of the law so again it is illegal to be carrying one in your car, and under PACE they have very broad powers in the searching of vehicle for such prohibited articles.

Now you know what is not allowed, I will point out that you can carry pretty much any knife (ignoring knives made illegal in more specific regulations such as automatic knives and buterfly knives) if you meet one o fthe following criteria:

1) you need it for work
2) part of your religion
3) part of your national costume
4) you can supply some other good reason

So under 4) you can carry a knife if you were going out camping and you needed it for bushcraft reasons. So in a specific incident you can carry the knife. The classic example is the Chief with his favourate butchers knives, he can carry them to and from his place of work, as he need s them for work, he can take them to his friends house where he is preparing a meal, as he has a good reason for needing them, but if he was carrying them into a nightclub, he clearly does not have a good reason and would be prosecuted.

I should note that the burden of proof is with the person accused to provide a good reason for carrying the item.