Grey-headed Wagtail at Cuckmere Haven - 12/6/13
Ashy-headed Wagtail in Italy (http://www.oiseaux.net/photos/michel.moschovis/bergeronnette.d.italie.2.html#monde)
Comparing the above two photos is actually quite difficult. The expected dark necklace effect is very evident in the Cuckmere bird, whereas the Ashy does not reveal this.
The supercilium behind the eye in the Ashy is very evident for a 1st summer/female bird, and I would have thought would have stood out more on the Cuckmere bird if there was any hint of Ashy.
http://www.manchesterbirding.com/greyheadedwagtailhybrideltondocmanchesterbirding.com.pdf - shows an adult which is believed to be a hybrid thunbergi/flava.
The image below has been brightened and contrasted beyond belief to get an idea of how dark the ear coverts are compared to the rest of the head. The dark eye stripe is still visible and the ear coverts are darker compared to the rear of the head, and the crown. Above the eye seems to be the darkest.
Grey-headed Wagtail in Cuckmere Haven