Anna saw this in the garden yesterday afternoon whilst I was having a pre-work ZZzzzzz.
I thought I'd better get a photo of it for her this morning, and identify it properly, although she described its name perfectly to me.
This is (almost) obviously the "Blue-Tailed Damselfly". I say almost, because there are other blue-tails, "The Scarce Blue-Tailed Damselfly" (but the blue patch on these males cover just segment 9, (the last segment) and the rear portion of the eighth (penultimate) segment only), not like in the photo above where the penultimate (8th) segment is the truely-blue segment..... and "The Red-Eyed Damselflies" (small and large), but these have, you've guessed it, red eyes.
That is why I'm sure this is (just) the (normal and very common) Blue-Tailed Damselfly.
But what a Bobby-Dazzler, as the mahogany-hued David Dickinson might say.
Click the top photo only to enlarge.