Rainham - Any ideas on Wader? not a lot to go on.

A walk with the kids along the wall to Aveley Bay and back at high tide didnt provide to much however the kids got to see their first Wheatear that was on the concrete river edge about half way between the reserve center and the bay.

 

Also an unidentifiable (for me) small wader flying up river; all i got on it was a small white wing bar, feet protruding from tail feathers, white rump with a darker center line/area seperating it in half and no white area protruding up its back. Also its flight action seemed unsmooth.