There are quite a lot of different species of caterpillar out and about at the moment.
This is an oak eggar caterpillar – I photographed this one on Woodbury Common last weekend
This is what they turn into – a male oak eggar
A female oak eggar
This is also a conspicuous caterpillar – people are for ever asking me what it is! It is the caterpillar of the mullein moth which feeds on the plant figwort.