That's fantastic Roy - this New Years day I took a group for a walk from Llanthony Priory in the East Brecons (Black mountains) and the small reservoir about five miles away looked like a lesser version of your photo. Wettest drought in history!
BTW - my honeymoon (I knew how to treat a girl!) was in the Brecons, and when we got out of bed (

) we drove around the Elan valley - good times, must go back soon.