I was getting in a muddle with brown butterflies and thinking that this was a gatekeeper or meadow brown. Then I found a really useful article describing the meadow brown, gatekeeper, ringlet (which I haven’t seen yet), wall brown, speckled wood, grayling, and small heath. It was very useful, and I realised that this little butterfly is a small heath.
The most obvious factor for identification is the size, which is smaller than the gatekeeper and meadow brown. That’s all very well if you can compare them in real life, but at the moment our watermeadow is full of brown butterflies and they are all the same size and look like this one!
There are other clues. You will notice that the butterfly has its wings closed. The small heath never settles with its wings open and rarely ‘basks’ in the sunshine. Its obvious eye spot shows through onto the back of its forewings and is a visible deterrent to predators. (link) The eye spot is a white dot on a black spot which is ringed with buff. Other clues are the grey margin before the brown edge of the forewings and the jagged brown line on the hindwings.
