Red-veined Darter (Sympetrum fonscolombii)
This is a migrant species that visits Somerset occasionally and so is rare. 
It differs from year to year how many visit the UK. 
Males are red in colour with red veins at the base of their wings, the lower half of their eyes are blue. 
Females are ochre/yellow in colour with yellow veins at the base of the wings, the lower half of their eyes are blue. 
It can be confused with the Common Darter and Ruddy Darter.  The key thing to look for is that the lower half of their eyes are blue. 
Currently, I am still awaiting to see this species, so I have no images of it.
Want to See 
No real places to highly recommend here.
Keep an eye on social media and see if anyone reports one and hopefully gives a location.
They do tend to like coastal areas, but can appear anywhere.

Especially Good
None to date

-----------------------------------