Any ideas? Very worn butterfly help

[Deborah]

Hello. I was out on heathland in hot sunshine today and amongst the tens of Graylings seen on the baked paths was this worn out butterfly. If anyone has any notion from this photo what it might be I’d be grateful. My thought was a Brown Argus but I’ve nothing much to pin that on!

[Butterflysaurus rex]

Hi Deborah, you have yourself a Long-tailed Blue there.

[Deborah]

Wonderful! Your reply sent me scuttling off to my books, and everything they say corroborates your ID. (If it hadn’t had been so tatty I’d be driving back out there tomorrow in the hope of another sighting!) Was it the blue/violet sheen around the body that identified it for you - given that there is very little left of its tails? Or something else? Thanks again.