As their name suggests these butterflies like holly. They can be found in trees and bushes. The one below was found in a flower bed in the shrubbery between the church and the main lake (on the holly of course). The under-wing is very different to the Common Blue, just plain with small black dots.

Their upper wings are a much better blue and usually darker than the Common Blue, so they do appear blue when flying. The female (below) has lovely black edging on her wings, although you can see this one has been in the wars and lost a few bits here and there. The male also has black edging, but much finer. The one on the yellow flower is a male (found beside the lake).