I thought the current law stated " bladed instrument" then you could be done for carrying anything sharp wih out good reason
Criminal Justice Act 1988 CHAPTER 33, Section 139, doesn't, as you can read for yourself, use the term "bladed instrument", though the phrase has often been used in learned and amateur commentary upon the Act and subsequent cases.
The "sharpness" is irrelevant -
Booker v DPP 169J.P. 368.DC set the amazing precedent of an offense for a non-sharp, non-pointed, butterknife blade. The fact that it was a fixed blade was all that it took for the conviction to be upheld and the appeal dismissed
You
can carry a sharp "bladed instrument"in public - so long as it is in the form of a folding (and we've been through the folding issue already) penknife with a cutting edge not exceeding 3 inches or should that extremely simple test fail then it up to the carrier to prove:
"good reason or lawful authority for having the article with him in a public place" and that the following are acceptable.
he had the article with him—
(a) for use at work;
(b) for religious reasons; or
(c) as part of any national costume.
But you'll still need a very good barrister to make your case.
Which can be done - This bit of kit
was being carried in a car (which is technically a public place) to a London nightclub. The jury at Southwark Crown Court considered that it was a perfectly reasonable thing to carry for religious reasons:
Student's flagellator was not an offensive weapon, court rules - Telegraph