Over the years, I have seen a few news reports on Wicca/Witch affairs. And out of them all, I'll have to say this is the 2nd most stupidest thing a Wiccan can do. When I still had my small spider athame I would only carry it when I had a rite, spending time in Nature at the woods, or in my house. Unless he had plans to do a Rite after going to a Pub, Like Dew said doesn't make since, then it is understandable.
England has a Act that allows Wiccans and Witches be open and do what they do. That is why they still allowed him to go out on Full Moons. Unlike the USA were they might not even think about it. But even so, an knife is still a knife.
If you like to know, I have seen a report on the news about a guy going to the bank and Hypnotizing the banker. That was what the banker told the police, that he asked for the money and he give it to him out of his free will. Not sure if he was a Therapist needing cash or a Wiccan. But it is still a good lesson to be learned, even if you can do it you can still get in trouble. Or so called Karma or the 3 fold rule.