As a Londoner, I don't agree that hospitals were just left. Northwick Park was the first to suffer and had patients sent out to multiple hospitals, so the situation stabilised in under 24 hours. We had ~40 ambulances go by when one hospital got overwhelmed and they were moving a raft of patients to the one near us. Playing in the garden in the sun to the constant sound of sirens was sobering. London also had the private hospitals and all their staff, taken over by mandate and caring for a lot of patients. Nightingales ready for overflow, skeleton staffed but with rumours of all manner of backup plans with ex nurse air crew, vets etc. CCGs must have backup plans for any normal winter and I can't believe CCGs in the NW and NE haven't developed any contingency plans, that just doesn't seem credible.
I also think we're far from herd immunity, and the continuing rises in boroughs that were hit hard in the first wave seem to indicate it's not the case.
Regarding NE and NW and the "too soon to leave lockdown" argument, I'm afraid I don't subscribe either. Cases were low, in many cases lower than some other areas, and changed erratically back up in the North. There are several airports that specialise in package holidays to the type of resorts that had clubs open and spread cases right across Europe and I think holidays contributed. On top of that we have idiotic behaviour, conspiracy theories, distrust in government (traditional labour supporting areas often hit hardest) conspiring to affect poor quarantine/ isolation compliance and compliance with tracing, excessive household mixing, deprivation, dense housing, idiotic parties, slow tracing of positive tests, more rainy weather sending people indoors often, a few local bars that didn't follow guidelines and a big dollop of very bad luck. If it hadn't started happening now, it would have happened in a month, two months... sometime before spring. Viruses just await opportunities; if you count each case that didn't transmit since March then we have hundreds of thousands of opportunities the virus missed to replicate at scale just in the UK, then it didn't miss. There is one thing I didn't include; if anyone has figures on number of people working outside the home during lockdown then that would be interesting, I recall checking the Google footfall maps and not seeing any particular differences. Other parts of the country also have deprivation and lots of people had to work outside.the home, I'm unconvinced NE and NW were special in that regard and instead wonder whether guidelines were followed in workplaces that were open.