So, neither one thought it wiser to - oh I dunno - maybe stay in the house and avoid the fight? And I have to ask, where were you watching this from? And did you call the police or just watch?
Wisdom and perspective I was at the pedestrian crossing with the old man who's stick was used, with my young son. He is now 30 so this was before the ubiquity of cell phones. The OP was about techniques and styles rather than wisdom (probably still in short supply among Peckham street thugs). Do you not think reach is a factor? The area is now covered by CCTV so maybe a style that incorporates municipal surveillance as an extension of reach would be a good idea.
first two moves I think that guy is called Alain Cohen. Some people make more of a reputation as trainers or training video producers than as fighters. Something that is often misunderstood inside and outside KM... In a drill the only really workable techniques are the first or the first two. Everything afterwards is icing - so here, that means the outer block and simultaneous punch to the throat. Assuming the punch landed square, afterwards there is no way of knowing where the attacker would be - is he coked out or uber tough and could he ignore the punch - shaolin monk style? Would he freeze and grab the defender? Would he stagger away and throw up, or gasp and cough uncontrollably, or grab his own neck in defence? If the defender managed to grab the wrist and land the knee a lock might be possible, but if that is the intended outcome of the defence then the defender will be so distracted that it would indeed be extremely unlikely. If the block worked but not the punch then he needs to hit again or run, sharpish. If the punch worked but not the block, he'd better hope the punch worked very well before he goes into shock. I think a good trainer will work as many possibilities as appropriate. Grabbing the wrist, landing a knee and applying a lock could be among these these - if only because they practice, grabbing, kneeing and locking. No magic bullets.
i didn't read the full thread but what i would say is forget what traditional martial arts train as knife defense. no one will hold his arm still so you can do wrist lock easily. in krav maga they train it more realistically. if theres a small chance to survive a knife attack without weapons, than it would be a forearm block with simultanously devastating strike, just to interrupt the stabs of a maniac. than maybe one can run or wristlock. but the likelihood to manage that in a surprising and death-fear situation is not very high, i guess... in knife-fighting they say, block the opponents forearm and cut his tendons with your own knife so he loses his grip. but well there's a lot would can go wrong fighting someone with a knife...