Seen on the Towans at Hayle, Cornwall, UK, and I know they are around there, however I didn't get a shot of the underside of this one. other undersides yes ( to follow ).
Thanks Pete. Here is an underside shot from the same location ( but different butterfly). Is this a Silver Studded blue as well ?, if so what gives it away ? - I did read they have spurs on their legs, but couldn't see any examples of that anywhere to compare.
The clue in the underside is in the name . It's unique in the UK in having those silvery blue spots along the edge of the hindwings which is where the common name stems from. (there are several species on the continent that share this feature). They do vary in how obvious they are but there's usually a few spots there. The one in your image has quite well marked so theres no chance of it being anything else in the UK. Habitat and time of year also help to narrow any questionable sightings down.
The spurs are a total irrelevance unless you happen to have a dead butterfly in your hands and you think it might be Idas blue. I have photographed them in living butterflies but I already knew what I was looking at!
In the UK, where Idas blue does not fly, the issue does not arise. You have lovely shots here of silver-studded blue.