This 9 April 2011 video shows how a ‘normal’ white wagtail looks.
The video says about itself:
White Wagtail – Motacilla alba (alba)
The race that breeds in continental Europe and is mainly only a passage migrant in the UK, where the subspecies “yarelli”, “Pied Wagtail” is the resident breeder. This bird filmed at Paphos Sewage Works, Cyprus, on March 31st 2011.