The 'American' wigeon was feeding on the shoreline right over on Musselwick side of the Gann in front of the large white house SM 81887 06646. It's with a group of 10 Eurasians, if they became nervous they would move onto the sea. So no opportunity to see underwing.
Park at the Gann, and follow coast path beside the pools and around the bay. NB Footbridge across river so check tide times (noticeboard by car park). Theres a group of 30-40 wigeon that stay faithful to the pools.