And after half an hour of stalking...

I've learned that some insects have very good eyesight (he spotted me every time at about 3 metres) and are quite jittery. I've also learned that crawling on your belly while holding a camera at the ready is not too easy! This guy is new to my garden this year and was first spotted yesterday. I'm guessing she is/he is a damsel fly rather than a dragonfly but the usual turquoise ones have transparent wings. Off to check the reference section! I thought s/he was rather handsome, with those beautifully marked wings.
OK. Settled with wings closed = damselfly but transparent wings =damselfly. Confused!
Added later: I'm told that it is a Banded Demoiselle, also called the "kingfisher" or "water butterfly". The wings have been probably "damaged" in some stage of its development. Or it just is a mutation.