It is especially important that this be looked at before any so called "crack down" on knife crime. The "presumption of prison" should not be applied to people carrying useful penknives.
The most common "leatherman" style penknife is the victorinox "swiss tool". It would be completely impractical for use as an offensive weapon (taking a long time to deploy and having a handle which makes it quite impractical for use as a weapon). If I was drawing the line between what should and what shouldn't be allowed then, my personal view would be that this multi-tool and multi-tools with a locking blade of similar length or smaller should be allowed.
Also take a look at the ideas on :
Many are quite sensible
This is lifted from there:
"The lock knife is bought by decorators, electricians, campers and a multitude of other members of the public who do not know that possession in a public place is illegal." Lock knives are tools, safer to use than pen knives, and there is no reason for adults to be criminalised for possessing them. According to the reporting in The Independent, MPs intended the allowed 'folding knives' to include lock knives, it was judicial activism that made them illegal."