I read I think it was Adam Kucharski who put forward one theory for the rapid drop in cases and why they MIGHT start bumping up quite rapidly again sooner than many would expect. A theory he put forward that was due to the extremely high case rates of the last few weeks, we've had so many people isolating that it's served in effect as a 'mini lockdown' ie with close contacts of many of those cases going into isolation and subsequently not spreading disease etc.
As I say, it was a theory and nothing more than that, but interesting all the same.