The female Willow emerald damselfly (Chalcolestes viridis). It has a metallic green body, and at rest, it holds its wings away from its body. Its common name is the Willow Emerald Damselfly or the Western Willow Spreadwing. It also has pale pterostigma (wing spots) and a green spur on the side of the thorax.
Willow emerald damselflies were first recorded breeding in the UK for the first time as recently as 2009, just a few miles south of Minsmere on the Suffolk coast.
The first image (taken in July 202) was probably the first one recorded in London that year.
Seen by the lake in the gardens of Chiswick House in July 2020 and in August 2023