Four-spotted Chaser (Libellula quadrimaculata)
Both males and females are very similar and hard to tell apart.
They have a brown abdomen which is black towards the end and yellow markings running along the base.
Thorax, brown at the top and yellow sides with black markings.
They tend to go quite dull once they have matured.
A slight variation is called a 'praenubila'.  In this form the outer spots look like they have been smudged across their wings, I have a couple of photos of these below.

Male
Male
Male
Male
Male
Male
Female
Female
Female
Female
Female
Female
Female (praenubilia)
Female (praenubilia)
Female (praenubilia)
Female (praenubilia)
Roosting at Sunrise
Roosting at Sunrise
Roosting
Roosting
Roosting
Roosting
Dew Covered
Dew Covered
Mosquito Waiting For A Ride
Mosquito Waiting For A Ride
Want to See 
Widespread, but definitely best in the Somerset Levels.
Likes ponds, reed-beds, rhynes, etc.

Especially Good
RSPB Ham Wall - Route 1 (Mid May / June) - Exceptional
Priddy Pools (Mendips) (June / July)

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