Thanks for the ID, Guy.
You're right, David, the species are coming on thick and fast in mid May.
See below:
Tuesday 12th May - Vitrolles - South of France - 23°C - hazy cloud
Lunchtime today up on the plateau of Vitrolles, there was an invasion of what I think are Provence Chalk-hill Blues.
I have only ever seen one before (June last year), which I took to be a vagrant, however today I saw 10+ males and 3+ females, before I stopped counting.
I don't know where they have all suddenly appeared from.
Could it have something to do with the fact that last summer the Council mowed the whole of this part of the scrub for fire prevention ?, and that mowing favours growth of the LHP (that I had never noticed before anyway) ?
Confirmation of the ID is welcome.
The females were particularly attracted to a spindly plant with yellow flowers, possibly the LHP ?
Individual No. 1 - male
Individual No. 2 - female - underside AND upperside
(on spindly plant - LHP ?)
Individual No. 3 - male
Context - plateau of Vitrolles (again

)
Spindly plant - LHP ?
Cheers, Chris