To expand on James' answer
From a forum reply regarding this subject(I forget which one):
"Under no circumstances, can you ever carry an offensive weapon in this country - but an offensive weapon can be a ballpoint pen, a bunch of keys, an apple - anything. Under UK law, an object - any object only becomes an offensive weapon, when a person either does harm with it or intends to do harm with it - not before. It's the persons intention that makes the object offensive, not the object itself".
If you are caught carrying a blade that the arresting officer deems an offensive weapon, the likelyhood is you will arrested and offered a police caution.Under no circumstances accept this caution as it is seen as an admission of guilt, i.e. You were intending to stab someone,or would possible use the knife in a self defence situation if one arose.This admission could possibly land you with a court appearance and a small fine in addition to the police caution.
I regularly EDC a Fallkniven TK3 and really dont worry about it.Why? Because the last time I was stopped and searched I was 16, and that was 19 years ago.However,if I was walking down the street dressed like Dr Dre or Enimem,or obviously drunk or under the influence of drugs I would expect to be stopped and searched immediately if spotted by the police.The majority of recent knife crimes are being perpetrated by 13-25 year old wannabe gangsters

As overzealous as the UK police are, I do believe they have the discretion about them to beable to distinguish the difference between who is likely to be a threat to the public and who is not.....however I maybe completly wrong.
Your main problem,I believe,would actually be getting the knife through customs at the airport you arrive at,Although,I know of a German guy recently visiting England for a deerstalking weekend,bringing with him a Fallkniven H1 for dressing game and had no problems whatsoever.
British Knife Law FAQ
http://www.britishblades.com/forums/showthread.php?t=8336
Ask-A-Cop, knives and related issues
http://www.britishblades.com/forums/showthread.php?t=2011
The sad state of the UK
http://www.bladeforums.com/forums/showthread.php?t=336748
FoxyRick said:
Not sure what it takes, but the Jedi tried it not so long ago. There was a public census and enough people put 'Jedi' as their religion (including me ) for it to actually be officialised. It wasn't though; never really found out why. Probably the damned government got involved!
http://www.theregister.co.uk/2001/10/09/jedi_knights_achieve_official_recognition/
And on a lighter note
http://www.theregister.co.uk/2001/04/10/may_the_false_declaration/
http://www.theregister.co.uk/2001/04/23/uk_jedi_get_green_light/
Sorry if I have waffled on too much, but I had to kill some time while waiting for my first busse combat knife(a FFBM)to arrive at the post office, where I am now heading to directly

So if I'm not heard from again...... I've been stopped,arrested and had the key thrown away. Chances are they would probably destroy the mistress aswell,or rather,they could try
Hope this helped
Bigbrick