Hot and sunny.
Close-up of the female:
This is another Chironomid fly - Cricotopus sylvestris - about 18mm long. It always perches with its front legs held out to resemble antennae, and the dark dots on the thorax give the impression of being the eyes of something much larger. (The actual head and antennae can just be seen below the thorax).
The first Small White I've seen in this area. Pieris rapae, just emerged.