No I am suspicious of them as well. The rise didn't seem unprecedented, we've seen that in other circumstances, but this sharp fall just doesn't look like anything we've seen before.
This is one of the reasons I'm trying to look at cases by age group in places where the pattern is different to the recent overall national and regional trends. More on that later.
In terms of the overall data, it was suspiciously sharp. However some of the data last week caused a subsequent bump that made the overall downward trend seem a bit more plausible. And the very peak of waves can feature some big spikes on top and the drop off from those can be very sharp, but drops of that sharpness dont last long.
Probably the safest bet right now is to assume that multiple things happened, and we cant be precise about any of them. For example something real probably happened to case numbers, but also one or more things happened that affected this particular form of data, at a minimum making it more extreme than the underlying reality.
Hospital admissions so far are compatible with at least a plateau, and should give clearer signals during the coming week. The laggy but still useful ONS population survey, based on testing a sample of households, should be a bit more useful when the next version comes out this coming Friday. And the data from the main testing system will still be interesting this coming week, even if we arent sure what to make of its recent performance. So I think we'll have more clues by the end of this coming week, although whether a coherent picture will emerge or not I cannot claim to know.
As for trusting the figures or not, its always better not to rely on a single measure to tell what is going on, especially when it shows something very dramatic. But I still have to pay some attention to it because the other forms of data that can back it up or give a different picture take quite a bit longer to emerge.
Plus I still cannot ignore what happened in Scotland, a reasonably impressive rate of decline that has been backed up by other data so far. It probably isnt too much longer before we see what clues Scotland offers about how the rate of decline may slow, whether number of cases gets stuck around a certain rate etc.
Looking at positive cases by specimen date graphs for Scotland and England, it is true that Englands plunge looked incredible and a bit absurd for a time. But a bulge of cases last week makes the overall downwards slope look somewhat less absurd now, it looks more like a decline with an additional chunk of testing/data missing from a period following the peak, but then a return to something more realistic looking. Whether my perceptions of how it looks have further to change still I cannot say either.