You have a Chaser (Libellula) of which there are three resident in the UK.
One has black spots at the wing nodes: four wing nodes, four black spots, hence quadrimaculata. Don’t be distracted/put-off by individuals of the form praenubila which have larger/stronger/smudged black markings.
Our 2nd has a distinctive, very broad abdomen. It has extensive dark patches on both fore- and hind-wing roots, the latter encompassing the discoidal triangle.
The last has restricted dark patches with only a hint, scarcely more of a thin line, on the fore-wing root and that on the hind-wing root stops short of the discoidal triangle.