A quick update is that the ring-necked duck was still present to at least this afteroon - all the details with this and the scaup (and it's half cousins) are on Erich's blog here.
Thanks to the finder, Tony Disley from InFocus Optics who sent us these much improved shots of the bird from yesterday:
site. Its the first time at Tophill for 8 years and the best bird of 2012 - so far...
A later edit: thanks to HVWG for this picture from today also: