Banded Demoiselle (Calopteryx splendens)​​​​​​​
These are larger than damselflies and can be seen a lot easily.
Males are metallic blue and their wings have a broad dark blue/black band going across them.
Females Metallic Green with a reddish/bronze tip to the abdomen, wings green.
I've also got a photograph of a more unusual one where the whole body is a red/bronze colour, including the wings.  This is the colour that appears normally at the tip of the abdomen, but for some reason has gone all over their body.  I haven't found any special name for this variation at all.  
Similar to Beautiful Demoiselle, male wings have a band across them.  In the female, the spot on the top of the wing is further back than in the Beautiful Demoiselle female.

Male
Male
Male
Male
Male
Male
Male
Male
Male
Male
Male
Male
Male
Male
Female
Female
Female
Female
Female
Female
Female
Female
Female
Female
Female
Female
Female
Female
Female (Unusual Variation)
Female (Unusual Variation)
Female (Unusual Variation)
Female (Unusual Variation)
Female (Unusual Variation)
Female (Unusual Variation)
Want to See 
They like slow moving rivers, streams and rhynes.
So very prominent on the Somerset Levels.

Especially Good
Yeovil Country Park (Riverside) (Late May / June)
Langport (River Parrett / River Yeo) (Late May / June)

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