Peacock Aglais io
Formerly Inachis io
Unlike the Small Tortoiseshell, Peacocks have only a single generation each year, the adults living from late July or August round to April or May, though they may be found flying in warm weather in any month of the year. They hibernate indoors as well as in woodlands, the dark undersides of both these species and the Comma serving to camouflage them from predators, though even so many are killed by mice and birds. .
Images L-R: upperside, underside; caterpillars on nettle
Flight period: Any month is possible but normally February or March to October or November, sometimes with a brief gap midsummer.