A new species for me

A walk to the village with the dog .produced this butterfly on the way back - a species I hadn't seen before. It appears however there are two alomst indistinguishable speices involved here and this is one of those two - Pale Clouded Yellow or Berger's Clouded Yellow. 
Easily distinguishable at the caterpillar stage - which is not very handy.
Either way a subtly pretty thing.