This little beauty returns every year in the lawn not far from the Iris reticulata. It's a mystery how it got there as it wasn't around for the first few years we lived here. There's something a little sad about the fact that it's the only one. It hasn't managed to have any babies. Ahhh.
It's a Blue anenome or Anenome apennina. It looks a bit purple in the photo but in reality it's more blue.
I wrote most of this last night but then couldn't find it in my Wildflower Key (see useful books) so hesitated (and so was lost) and went out until very late.
Today I've tracked it down and am sure of the identity (from internet and Stace).