This chappy was found mid afternoon along the river bank south of Exceat Bridge. Obviously very noticeable straight away with no supercilium, dark blue/grey head and pale throat with yellow strongest on the vent weakening out up to the upper breast. With these features combined, there is potential for it to be a 1st summer Grey-headed (Yellow) Wagtail.
The pale throat is very misleading though 1st summer birds can show this, see http://www.birdingworld.co.uk/CleySpring2007.htm .
On the right side of the head, close ups reveal some very disjointed white marks. The white mark nearer the base of the bill is a feature of thunbergi, with other pale marking possibly showing characteristics of Ashy-headed Wagtail, but this would stand out much more so. http://birdingfrontiers.com/2013/05/13/grey-headed-wagtail-id/ shows a female which much more white above the eye, so I would imagine a 1st summer male would show this also.
Anyway, comments welcome and i'l dig deeper for more info.