Apart from the deep red colour, the body shape is key to separating them from Common Darters...
And they look menacing close up!
I was lucky to find this immature male!
Exactly the same structure as the adult but the immature bright yellow ochre colouration will eventually turn red...
Now then, what have I stumbled on here? A female! There is no 'waist' to the body which gradually tapers and the colouration is paler
To exclude a female Common Darter, note the all black legs and the T-shaped mark at the top of the thorax
There's a lot going on in the Odonata world at VP and it's right under your nose :-)