There's been a few rumours all day about how bad Johnson is from political twitter.
Johnson appearing on the doorstep on Thursday looked like he'd just got out of bed for it and it was a move to reassure the country he was OK still. I believe the announcement of the Queens speech was around then too (it was pre recorded so could be used whenever it was felt most appropriate).
I find the queen's speech broadcasting at 8pm and the Downing Street announcement almost exactly an hour later at 9.10pm that the PM was being hospitalised very striking.
I don't know if its coincidence. (I'm generally not a big believer in that in politics). It almost looks chorographed so our head of state gave reassuring words as our prime minister is taken to hospital.
It could well be that a couple of days ago they were starting to have concerns with his ongoing symptoms and inability to end isolation so started contingency planning deciding that he should go to hospital today as a precaution if he still wasn't improving as he would be heading towards a point where they would be getting concerned that he was at risk of deterioration anyway. A planned exit to hospital rather than an emergency one is a lot better in terms of both national security and in terms of preventing panic within the country.
So yes. I do think that those close to the PM like Hancock probably knew how things were going to pan out this evening.
It's just a little too convenient otherwise.