I find the identification of duck a little bit tricky, with some species of Duck readily hybridising only adding to the potential pitfalls. Today, I chased a duck around Eglwys hoping to get a better view. My hoped reward for this effort was a Lesser Scaup. Not this time.
My final conclusion is that the bird in question is a Scaup x Tufted Duck female. In the end it allowed me to take a few photos of it, as you'll see the light wasn't great! One thing the photos don't show is that the bird was similar in size to a Tufted Duck.
Also on the Reservoir today were 3 Scaup drakes (1ad + 2x1stw) and 55 Goldeneye. Good news also on the Bittern front as I was told it had been seen in flight on Tuesday by David Benjamin