There were play cells last week, nothing charged. These were removed on normal inspection.
thought they are sealed on day 8 though?
Important to distinguish between 'Play Cups' and 'Queen Cells".
Both in understanding - and in the hive.
Play cups - you don't normally get a lot of them at once.If you have a bunch of them, look closely for eggs!
Queen Cells are indeed normally sealed on day 8 after the egg in question was laid.
In your eradication effort, if you had missed even one "play cup with an egg", and the egg you missed was 3 days old, then you'd only have 5 days before sealing (and normal swarm departure).
Knocking down QCs is generally counterproductive.
2 of my hives had capped QC's and and few other cells were charged. Tried an AS on one. The other had to tear down ...
Have a read ==>>
www.wbka.com/pdf/a012queencells.pdf
Destroying queen cells to prevent swarming never has been and never will be a successful method of swarm control. If you destroy one lot of queen cells the bees will immediately make some more and will probably swarm earlier than normal in their development - often before the first cells are sealed. If you destroy queen cells twice you run the
risk of the colony swarming and leaving behind no provision
for a new queen. Any delay of swarming that you induce by destroying cells will probably result in the prime swarm being larger than it would have been if you had not interfered.
Why hadn't a swarm gone, even though QCs were sealed?
Maybe simply that the weather wasn't good enough.
Departing any time while the cell is sealed is perfectly possible. They have an 8-day window of opportunity. They don't HAVE to go the moment the first cell is sealed. But they could. And if QCs have been "torn down", they may not wait for the next batch to be sealed ...