What is this bird?

Hello

I first saw this bird during the bird watch at the week. Through binoculars it was completely white with a few grey specs.

The picture below (terrible I know) is the best I could get with my phone when it returned very briefly. The bird itself is on the branch next to the hole in the feeder.

I am know with all the usual garden birds but this was something I have never seen - my best guess is an albino chaffinch?!

Any ideas what it could be?