Dave
You seem to have a problem with denominators. The denominator for 100,000 deaths is not the total population of 68 million UK residents but the UK, but the 3 millions who are positive for the virus, which makes it around 2.7% IFR. And that is the reason why the number of deaths keep rising and that and the proportion of positives is also rising more rapidly than the increase in UK population. In Fact according to your false positive PCR hypothesis, as the number of SARS-cov2 positives is overinflated then the IFR must be more than 50%! Have you though that one out?
By the way thank you for this very valuable link.