Being so common I've never paid too much attention to ID of pied/white wagtails but took a couple of pictures of this bird last night and it struck me as unusually dark, although it was towards dusk and the light was fading. Can anyone offer an opinion if this is an alba or yarrellii wagtail? I ask because of the dark grey mantle and dark flanks that makes me doubt the typical white wagtail from this area. 
