Female Common Blue

I spotted a brown butterfly which turned out to be a female Common Blue. Checking distribution maps it seems that in any case we don't get the Brown Argus here (although it is found on the coast 20 miles away or so). Telling the difference between the browner versions of the female Common Blue and the Brown Argus can require close observation. However the presence of some blue on the upper surface and the presence of dots on the in the bottom half of the underside of the forewing indicate it is a Common Blue and not a Brown Argus.