Hmm, as a police officer I carry a few knives about my person on duty. You'll find a SureFire Delta in my trouser pocket along with a UKPK and a Leatherman in my bag. (the Delta replaced the resuce knife I was issued as I didn't think the lockup was good enough but that's an aside). And off duty you'll normally find the UKPK at least somewhere attched to me and probably my BM Stryker.
Whenever I've stopped and searched someone and found a knife on them I've asked the normal questions (why do you have/need this knife) and if they've given a valid reason they've been let on their way (apart from the time I stopped someone carrying a Strider SNG and then the person was detained for half an hour talking to me about knives).
If I'd been called to this incident then I'd have just given him words of advice and asked the guard to store his knife for him.
I can't help but wonder if Mr Reed took the caution because it was the "easy way out"..
However to recall my own stop and search experience at the hands of the Transport Police I have to say that all police officers are aware of every single law out there. I spent a few very heated minutes explaining to them that my UKPK was very legal and the SF Delta was carried because of work.
Oh and hello again Marytn