I'd not seen Chalkhill Blues before. What a butterfly! Some of them have the most intense azure next to the body, but the rest of them are beautiful sculptures of pale blue with brown surrounds. There were quite a few too by the path from the car park across the road and up to the mounds. I would estimate 50-100.
Also Dark Green Fritillary. I got my first decent view, and very nice it is too. Almost a black-and-white effect on the wing edges. There has been a record reported from Hatfield Forest so I need to do some careful studying here.
Otherwise, a Knapweed Broomrape (no photo) and a Skylark.