I have to point out observations and/or strongly disagree with some of what's been said:
1. Though I cannot deny (necessarily) that a stick of some sort is equal to or possibly superior to a knife, the reality is that its entirely impractical. I cannot carry a stick everywhere I go. I CAN however, carry a folding knife. I can carry a gun a lot more places than I can carry a stick, and a knife even more places than a gun (the beach / lake, for example).
2. A folding knife is an excellent, outstanding, quickly deployed, formidable, deadly weapon, with rapid & multiple strike capability, ****IF*** you don't have a gun. Again, a folding knife can be carried completely concealed whereas a fixed blade knife ordinarily cannot (except for a neck knife, of which I am a big fan). A fixed blade worn externally is only "PC" in certain very limited places. Sure, in an ideal world, a fixed blade is better, but a
Do not discount the deadliness of a sharp, sturdy folding knife (with a good locking mechanism and sure grip) in agile hands.
I do agree with the (a) bring a gun, and (b) run like hell if you have a chance. But (b) is true in ALL self-defense encounters. You should always AVOID if possible.
If I think I'm going to a place where I have an unusually high chance of an incident and cannot carry a gun, I like my Gerber Applegate-Fairbairn folder, which I've made into a 2-edge, or my CRKT "Desert Cruiser" which has the LAWKS system to ensure that it cannot fold while employed. For everyday, the Kershaw Leek, Avalanche, or Spec Bump is carried. I would bet that I could kill someone very quickly with my razor sharp Leek, should I be attacked - even though the knife is relatively small, it's long enough to reach vital organs and slim enough to easily pierce.
I'm sorry to hear about the state of affairs in G.B.
I'd have a 3" folder (non-locking) and work on that inverted technique, focusing on slicing, not stabbing, so that pressure is always working against the blade's opening direction, not against its closing direction - nice technique...