Pied or White Wagtail

I saw this juvenile wagtail at Clumber Park this afternoon.  I am presuming it is a pied wagtail but just wondering if there was any chance it could be a white wagtail or whether this is just wishful thinking!  They both look very similar in my bird id book.  Thanks.

 

See my Flickr photos here

https://www.flickr.com/photos/115745582@N04/