First, quibble with the headlines. For the benefit of Times readers, half past seven is not rush hour in Luton town centre. The only people around are those few of us with early starts in London (I aim to reach Canary Wharf for 08:30), and preparation for the business day: cleaning windows, stocking shops, etc. The most coherent account of what happened was that a window cleaner who had been working at M&S was attacked while using the ATM at the Town Hall end of George Street.
The (premature) conclusion is that this was a freak. It's extremely rare for a police officer to be fatally stabbed while dealing with day-to-day street crime. I wouldn't like them to go into life-or-death mode every time there's a fight in the high street. If firearms are around they go into full combat mode and that's a different matter - it's a whole lot more dangerous for them and they have to be extremely cautious, which is unpleasant but reasonable. But I would hate to see them acting more "militarily" and less humanly whenever someone has a knife. It would cut them off further from the population and perhaps in net even make them more at risk.
Of course, if I in my comfortable safe job say that the risk of this happening is so small that the police ought to continue to run it - that is, that there should be no reaction of a general kind (changes to procedures, etc.), I must - and do - accept that the specific reaction to this death can be large. After all, if it's so rare, then we can afford it. I will make sure I remember the name of Jonathan Henry, and remember that he left a family who deserve special respect in Luton, for years to come. Attacks on the police are more serious crimes because they threaten to separate the police from the public in the way I discussed above.
I don't know whether the large-scale investigation taking place of what seems a straightforward event is just overkill, or a routine response to the use of the baton round, or a routine investigation into how an officer came to be killed. In any case, it is OK. The figure I saw on the ground at 7:35 looked pretty comprehensively disabled, but having been under-cautious the police would have had to jump to being over-cautious.
If the figure on the ground was PC Henry, then there was a screw-up, because one ambulance was already leaving, and another waiting. But I'm over-speculating now. I'll continue to follow the story as the facts come out.