Sunning themselves by an ornamental pond.
No interactions present.
I was a bit undecided because of the colour, but the distinctive black marks on the 8th and 9th segments swung it for me.
The best features are the legs, which never have a yellow stripe running along their length in Ruddy Darter (though can appear all dark on some aged Common Darters), and the extent of the black at the sides of the frons (face) - the black clearly extends down the side of the face on Ruddy, but is only along the top of the face on Common.
The black marks on the dorsal side of the 8th and 9th abdomen segments can be equally distinct in both species.
I obviously need to learn some more about dragon and damselflies.
Lat/Lng: 51.4397, -3.3048
OS grid ref: ST094719