Just finished reading this thread , all 42 views.
Apart from the very different cultural aspects between the UK and the US, the precieved threat (real or imaginary) is also entirely different. Whilst I disagree with Uk law on carrying knives, I could not honestly justify to myself the need to carry one in the name of self defence.
I live and work in Leith, the docks area of Edinburgh, a working class, but proud area of the city. Most trouble is sorted by fists. It is a rare and headline grabbing event if there is a stabbing. There is no pride associated with, or street cred gained within the community by carrying a weapon. I would be a foolish man to brag about or pull a weapon out in anger - I would be asking for more trouble than I could ever dream of dealing with.
To be truthfull I'd be better off learning a martial art.
I say this in relation to my community and city, and cannot comment on other areas.
To gain a greater insight to the real trouble makers, I would recommend the link below - humourous but true.

http://glasgowsurvival.co.uk/

{Definition - NED = non-educated delinquent}

Oh... I carry a leatherman squirt on me...