I think anyone in most of the States, even the most anti-victim ones like New Jersey, is in a poor position to advise a UK citizen on use of force. The UK makes New Jersey look like the Wild West.
See, if some whacko I didn't know attacked me on a city street at 2 AM in the US, he'd be very lucky if I didn't let some air out of his neck. I'm not saying that's a good thing, considering that lima got out with no blood on the sidewalk and no charges pending and no angry chav looking to avenge his brother. I can't say that would be the case if it had been me.
But where I live, a law-abiding citizen can walk around with a Buck knife and a .357 on his hip, and it's the deranged, unemployed dope fiend attacking you in the street who is considered the criminal. UK lawmakers think we have that backwards. So I have no idea what I'd do in lima's shoes. Probably what he did.
Still, even though mere possession of a blackjack or pocket knife would probably get you 2 years in the UK, there may be options. A stout little metal flashlight or pen or umbrella or even a hairbrush is a huge improvement on bare knuckles and may not be considered an "offensive weapon" in the UK. I say "may not" because the authorities there are so fucking insane, I don't know what they'll say next.
Maybe you can dream up a professional reason why you need to have a screwdriver or wrench on your person at all times.
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