Interesting Aythya hybrid on W lake Cosmeston this morning. Looked superficially like Lesser Scaup, but had bronzy tinge to head and was slightly bulkier than Tufted. When Lawrence arrived with his scope, the balck bill nail could be seen the too extensive. Nape was flat-ish but not flat enough IMO although it did have the small bump at the join of nape & crown. Back was nicely vermiculated grey. You have to wonder whether the regular Lesser Scaup is cross-breeding.
Also present of interest, 1 drake Wigeon and 3 Gadwall
Glamorgan Bird Club 
It sounds rather like the one that was hanging around the wetland reserve then Hamadryad Park earlier in Jan. Have a look at my post from 19 Jan, I posted a shot of it.
Thanks Peter. In fact neither Lol not I thought it was the CBWR bird. Wasn’t quite as bulky and just had a different ‘jizz’, and we’d both seen the Bay one. Who knows?