Hello,
I agree with most of what HK says.... apart from McDs!! They're not that bad, better than BK. If you want truly BAD Burgers, Try McDs in the South of France.
Carrying a blade legally in UK, is OK - 3" Max SHARPENED EDGE, therefore, the blade may be longer, but not have a sharpened edge of more than 3". I have on one or two occasions ground flat part of an edge, to make it legal for EDC. You may have a problem explaining this to a policeman, but nevertheless, that's what the Criminal Justice and Offensive weapons act states. He'll be impressed that you know more than he does.
Liner and spine locks are OK, so long as you keep them in your pocket. The blade does NOT become locked, until you physically lock it.
Fixed blades are forbidden, unless you can prove reasonable cause for carrying it. I can't think of any that would be accepted for carrying a neck knife, or concealed fixed blade, of any type. You will be arrested on the spot... but then soon thereafter, released on bail to appear at a Magistrates court. Expect a fine of at least $75, but you won't go to jail. There is no such thing as bail surety in UK. You could be bailed after committing murder, on your own promise to return. Civilised, aren't we?
Using a knife as a weapon of defence..... illegal here, as it is in US. Anything, even a pencil, when used as a weapon, changes status. The most innocuous article becomes a 'weapon of offence'. Certain items are classified as OFFENSIVE weapons, which are a different kettle of fish, but a 3" pocket blade isn't one of them. A fixed blade is, however. Use one as a weapon, and you WILL go to jail!!
Pepper sprays, mace, pepper powder, tear gas pens, electric stunners are all OFFENSIVE weapons in the UK, though strangely, easily obtainable.
BTW, I checked out the above facts, with the Home Office, and they are correct. Most UK laws, are a matter of interpretation. Use a knife as a defensive weapon, and you will be arrested QED. Having said that, if you did not start the fight, UK law gives you the right to use 'reasonable force, and take reasonable measures' to PROTECT your OWN life, and that of others, dependent on you. If this is the case, you will be released, following a short formal procedure. The knife though, is history.
Most of all though, remember this.
You will NOT get searched by the British police, unless you do something to arouse their suspicion. Most police officers will probably let you get away with a reasonable EDC blade of say 4". It is not worth the paperwork, or time taken to prepare a caseto prosecute you. British police officers ALWAYS have discretion.... be polite and corteous, and you should be OK.
I have walked the streets of UK for over 40 years, London included, and have yet to be stopped by the police, never mind asked to empty my pockets.
Here is a tip. It is NOT illegal to posess any bladed weapon in UK, indeed shops sell them quite openly. If you purchased one, new, or second hand, how are you going to get it back to your hotel? Carry it of course.
Have a good holiday
Doug