Simply carrying a knife is not a crime.
Er, it can be.
From:
www.gov.uk/buying-carrying-knives
Basic laws on knives
It’s illegal to:
<span class="italic">sell a knife to anyone under 18, unless it has a folding blade 3 inches long (7.62 cm) or less</span>
<strong>carry a knife in public without good reason, unless it has a folding blade with a cutting edge 3 inches long or less</strong>
<span class="italic">carry, buy or sell any type of banned knife</span>
<span class="italic">use any knife in a threatening way (even a legal knife)</span>
(contd).
As you would expect, courts have a very strict view on "reasonable". And indeed "public".
(Cached version as original has disappeared)
<a class="break-all" href="https://webcache.googleusercontent.com/search?q=cache:L1n_E3Z6rWwJ:www.express.co.uk/news/uk/169587/Man-with-penknife-in-his-car-is-handed-a-criminal-record+" rel="nofollow" target="_blank">webcache.googleusercontent.com/search?q=cache:L1n_E3Z6rWwJ:www.express.co.uk/news/uk/169587/Man-with-penknife-in-his-car-is-handed-a-criminal-record+
Full-time carer Rodney Knowles, 61, used the multi-function Swiss Army-style knife for picnics during camping trips in the countryside with his wife.
Police discovered it alongside a torch, maps and a first aid kit when they searched Mr Knowles’ car after he had passed a roadside breath test.
Mr Knowles, who walks with a cane and is registered as disabled, was hauled before magistrates in Torquay, Devon, on Wednesday and, following legal advice, admitted possessing an offensive weapon.
He was given a conditional discharge. But the conviction will stay on his records.