Though in flight the back on this bird looks pure grey, on the water it was possible to make out dark markings on much of the upperparts feathers.  I did wonder whether this was a retarded second year, but there were several birds around like this and they were the least adult-like of all the birds present that day (around 15-20).  Also the tail, with fine banding, would seem to clearly indicate a first winter bird. This bird was also present at the same site, but has a somewhat different tail pattern.