@chatterbox That assumes 100% are vaccinated though, which is never quite going to happen. I think the estimates on the proportion protected from hospitalisation are mostly a bit lower than 99% too. If you have only 95% protection from the vaccine, plus a further 5% of people who are unvaccinated, that's about 5.7m people at risk, and if 5% if them require hospital that's 285,000 (if they all catch it) which is enough to overwhelm the NHS again if over the space of a few weeks or months.
The wider group spreading it around in this scenario would be the 13m under 18s, the 6m unvaccinated and, maybe 10% of the vaccinated - another 6m, so total of 25m spreaders, minus a bit for those who've had it already, so maybe 17m spreaders - enough to keep a virus going if it has a natural R if more than about 4.