"I thought you might be interested in the attached photos of hibernating Peacock butterflies. They were taken in a disused tramway tunnel, which carries a public footpath, at Ticknall in South Derbyshire. There were 28 Peacocks and around double that number of Herald moths, one of which is shown, in a tunnel about 120 metres long. There were no clusters of Peacocks but well spaced groups in the most sheltered spots - there was quite a breeze blowing through the tunnel. Shelter was provided by roof supports and stepped side walls at changes in tunnel diameter. Not often you can see 28 butterflies on a January day!".
And a photo from Alan:
