This week as usual, I did the Tuesday and Thursday dawn to dusk on Reedy fen, two different days.

Tuesday started cold and overcast with rain moving in off the west-south-westerly winds around an hour after first light, it wasn't heavy or persistent. By nine o'clock it was sunny periods, the sun was warm, not hot, fish were rolling everywhere.
I had two runs, mid-morning and around three pm, by late afternoon the rolling had stopped and the evening was quiet.

I returned on Thursday at dawn, the skies were cloudy and overcast with a light west-south-westerly blowing down the lake, it was warm. I spotted a couple of fish roll in the first hour. By mid-morning the sun was out and the wind began to build to a moderate blow. I never saw another carp roll for the rest of the day and the rods remained silent.

Similar conditions, perhaps today wasn't quite as good, Wednesday was sunny. Often when the carp are preoccupied on naturals they will breach to clean off the silt, so I don't think it was that otherwise I'd have spotted it. So it had to be something else that preoccupied the entire five acres and all the carp in it.
Anything that can do that has to be a big player, temperature perhaps?
It is certainly something I've witnessed before, we all have, the lake just switches off.
Thankfully Tuesday was good and I managed a super 25.10lb mirror 😉