Well I think its a Gipsy moth but I am not 100% sure. This one was crawling across our patio table, so no clues as to what food plant I found it on, unless it likes tomato and endive salad, mixed charcuterie, fresh bread and a glass of 1664. Probably not.
I put him on a nearby Hazel bush and took his photo.
A word of warning the hairs of some caterpillars can cause skin irritations so best not to play with them, but I am fairly thick skinned so just moving it from table to hazel bush was fairly risk free.
There is a web site which might help you identify caterpillars and it is http://www.mothscount.org/uploads/caterpillar%20lft.pdf
To see other photos I have taken click Alamy Photos