Damselfly - but which one?

At a quick glance, White Legged Damsel

Thanks for this suggestion. As I went to compare against images on the British Dragonfly Society website I came across an image showing a female Blue-tailed damselfly which looks remarkably like the one I posted. The information suggests that females will change colour as they reach sexual maturity and that is why the colouration in my photo is not the bright blue that you would normally expect with this species. (See the section on their website that is under Damselflies - age). Cheers, Steve