I believe the plumage is within the normal range of variation of Grey Wagtail, which is limited anyway for a male in breeding plumage.
There are three subspecies: nominate cinerea, particiae and schmitzi. The last two occur on resp. Azores and Madeira...
There are however populations, which do show differences, albeit very little and with some overlapping (e.g. tail length). My understanding is that these populations are not or not by everyone regarded as subspecies that can be identifiable in the field.
