Keeled Skimmer (Orthetrum coerulescens)
These are a slightly more unusual one for Somerset and harder to find.
Males have a blue abdomen when mature and blue/grey eyes.
Females have a ochre abdomen.
Immature, the abdomen is yellow and males and females are very similar.
The main confusion will be with the Black-tailed Skimmers.
The images below are split between Somerset and the New Forest where they are in much more abundance.

Male
Male
Male
Male
Male
Male
Male
Male
Male
Male
Male
Male
Male
Male
Female
Female
Female
Female
Female
Female
Female (Mature)
Female (Mature)
Female (Elderly)
Female (Elderly)
Female (Teneral / Newly Emerged)
Female (Teneral / Newly Emerged)
Female (Teneral / Newly Emerged)
Female (Teneral / Newly Emerged)
Female (Teneral / Newly Emerged)
Female (Teneral / Newly Emerged)
Female (Teneral / Newly Emerged)
Female (Teneral / Newly Emerged)
Mating
Mating
Want to See 
Likes heathland and mires in the uplands of Somerset.
Exmoor tends to have the best places in my experience.
The Blackdown hills and Mendip also have them but in smaller numbers.

Especially Good
Pinkworthy Pond - Exmoor (Mid July / August / September) 
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