White Wagtail - Whitesprings Plantation

The Pied Wagtail is a common resident in the area and winter roosts at the Endhoven works can number several hundreds. Its European cousin, the White Wagtail, is a regular spring and autumn migrants in Derbyshire and is primarily associated with wetland areas so it was a surprise to find one feeding on one of the recently felled areas at Whitesprings Plantation this morning.

White Wagtail (Motacilla alba alba)

Identification is easiest in the spring when there are no juveniles around.
Key features are the pale grey mantle, pale flanks and greyish rather than blackish rump. 
The relevant area of the rump is generally taken as that adjacent to the middle tertial.
Note, however, how the colour of the mantle varies in these photos with the angle of the bird and changing light. The lower bird in the bottom photo looks distinctly darker than that in the top most photo.