Just copying Angryrant's post here as it is useful.
"Kate McCann - 'For those asking/concerned about PHE figures on covid-19 deaths and why the number yesterday was low/why the way it is reported has changed, here is some more information:
NHS has been providing figures to PHE on covid deaths by 9am every day and PHE then publishing stats at 2pm. That was the intention. But as deaths rise it has become difficult to collate and verify the numbers in time. That has led to figures being published after the 2pm deadline. To get on top of this, PHE and NHS have decided to change the time these numbers are reported to allow more time to check they're all correct. Importantly, the way the deaths are collated has not changed, only the time. [I am still waiting to hear what the new cut off time is, and the new publishing time]. As a result, yesterday's death stats looked much lower than expected but unfortunately that was a crossover day when the times were being altered. So today the stats are likely to look far higher. To give a more accurate picture (although I appreciate this is not ideal, stats experts) the suggestion is we add up the figures from yesterday and today and then divide by two to better understand what is happening. There is also likely to be a note published later from officials to explain this formally, so that people can rest assured there is nothing funny going on with the numbers here.'"
I make it roughly this (these figs may be slightly wrong, but roughly right):
23rd - 54
24th - 87
25th - 43
26th - 115
I then, as suggested above, take the average of 25th and 26th = 158/2 = 78 for both days. Obviously that is not the 'correct' figure but would be a rough approx. Of course you can't read too much into a few days figures anyway. Perhaps the official note will explain more.