Tricky one. Could be a leucistic Great Tit or or even a Blue Tit. I think I would favour the first. Bluey/black legs would indicate to me one of the tit family.
Best to wait for further opinions though
____________________________________________________________________
Tony
My Flickr Photostream
For advice about Birding, Identification,field guides, binoculars, scopes, tripods, etc - put 'Birding Tips' into the search box