Apparently not.It is an offence to have a knife ( "any article which has a blade or is sharply pointed" except a folding pocket knife where the cutting edge of the blade does not exceeds 3 inches ) in a public place.
It's a defence, in any case, for a person charged to prove that they had lawful authority or reasonable excuse for having the article in a public place.
In your case, without prejudice to the above defence, it is a defence for the person charged to prove that they had the article with them a) for use at work b) for religious reasons or c) as part of any national costume
Your knives appear to fall clearly within (c) (and may also fall within (a) if you pipe for a living!)
Note that these are defences.Any police officer is expected to apply common sense and ought not bother when the case clearly falls within (a) (b) or (c). The CPS would never let you be charged anyway when the case is obviously within them.
[The law referred to is the Criminal Justice Act 1988 section 139 (1) ]