Males are black with a blue tip to the abdomen; segment 9 is wholly blue; segment 8 partly so.   Mature females are black or greenish-brown; imature females are orange.

Very similar to Blue-tailed damselfly Ischnura elgans.

Good field photos of male showing tip of abdomen needed,  We recommend that your record is confirmed by an expert before submission to Naturespot

Near Threatened on the British Red List  for Odonata (2008).

Rare.

https://british-dragonflies.org.uk/species/scarce-blue-tailed-damselfly/