White Wagtail

There seems to be  a convention going around that if you can't make up your mind if it is a Pied Wagtail or a White Wagtail then you just call it an Alba Wagtail. I'm fairly certain this is a White Wagtail
I've been chasing this one for about 6 weeks and only today did he decide to stay still long enough and close enough for me to get a decent shot of him. There is also a Grey Wagtail in the same area but he is having nothing to do with the Paparazzi.