You have one of our two Sympetrum species with light longitudinal stripes running down the legs.
This means either Common Darter (Sympetrum striolatum) or Red-veined Darter (Sympetrum fonscolombii). Observations of both, in England, at least, are quite widespread but the Red-veined Darter is much less numerous.
The pattern on the side of the thorax differs quite noticeably and the Red-veined Darter has quite strong black running down the side of the frons whereas the Common Darter does not. 
Allowing a brief foray into colour, for mature specimens there are a couple of gender-neutral differences which are quite clear: Red-veined Darters of both sexes have a blue-grey underside to the eyes and yellow pterostigmas edged fore and aft in black
 Several hopeless [personal opinion] identification apps have demonstrated a predilection for identifying Common Darters as Vagrant Darters/Moustached Darters (Sympetrum vulgatum). As the name Moustached Darter implies, the latter does have black running down the side of the frons and looks otherwise very similar to a Common Darter. However, whilst being quite prevalent sur le continent, Moustached Darters are rare vagrants to the UK. There have been 66 accepted records, the most recent in 2013.