This is the Heath Fritillary, one of the UK's rarest species of butterfly. They are confined to just a few colonies in the UK (mainly Exmoor, Essex and Devon) and probably only number a few thousand specimens in this country. Fortunately for us Blean Woods Nature Reserve just outside Canterbury is one of the very few colonies left and this year the numbers are up. They thrive in coppiced woodlands where cow-wheat grows, quite specific conditions.
This beastie my have nothing to do with Dover, but I thought it might be nice to show a picture or two given it's rarity and threatened status.