March 12th 2020 11:19am, Lincolnshire.
By March 12th, I had not seen a Peacock butterfly on the wing yet.
This picture was taken in an underground bunker where air temperatures were cool and not fluctuating much in weather app lunchtime, sunshine warmth.
That meant, the Peacock was still hibernating and not in a temporary, rough weather roost. The picture was taken when the internal light was turned on (which didn't appear to disturb it).
I agree with many of you that it seemed to be a good year for the life cycle of the Peacock. For example, I saw many butterflies while working on an allotment near the end of March and April, when weather had warmed further. I thought that people start to notice them in afternoon, lunchtime warmth, when general weather app. temperatures were predicted above 15ºC, allowing for some extra micro-climatic direct sunlight warmth, in those sheltered, direct sunlit places. As you might understand, because of those variables, my science wasn't exact. It wasn't so much fun in looking for them on the wing, if one was not going to see one, anyway, unless one was disturbed, (which was nothing much to celebrate, within "Butterfly Conservation").

A science here was to set up a micro climatic, local air temperature, accurate thermometer, without influencing the temperature oneself or disturbing a butterfly, then use time-lapse technology, similar to that of pupa emergence, or motion sesnsor triggered cameras, to accurately record local temperature on hibernation emergence (Butterfly flying towards the light). It was guessed, that most Peacock butterfly populations responded in the same way, to similar local temperature increases.
Kind Regards,
PS. The best purpose built hibernating places had dark looking entrances to attract the butterfly from a lighter space and once entered, did not trap a butterfly on a window, when it was time to leave, flying towards a light source, that might have changed position slightly, according to the direction of sunlight, from the apparent position of the sun in the sky.