A sunny bimble

Yay, Summer has finally reappeared and G, M, V & I made the best of it with a lovely bimble around College Lake in Tring.  Not many birds to be seen today, but the sun did bring out lots of butterflies and bees.  The photo is of a Gatekeeper, but we also saw lots of Peacock and Comma butterflies, as well as several others too quick to identify properly.  The flower it was sitting on was attracting lots of butterflies and bees, does anyone know what it is?

"Happiness is a butterfly, which when pursued, is always just beyond your grasp, but which, if you will sit down quietly, may alight upon you."
Nathaniel Hawthorne