Guessing is always fun. : )
The fact that it is white and black cuts out any birds that will grow up to be red or partridge. I'm guessing it is standard sized because of the proportions of the head and body (sort of like a pony to a horse it seems bantams are to standard chickens). It doesn't have a crest, feathered feet or extra toes, which also cuts out a great deal of breeds. Barred breeds will usually be mainly black with white on the head and chest, so I'm doubting it is barred or cuckoo. It doesn't have dark legs so I don't think it would be a Black Giant or Australorp unless it just had poor genetics.
My guesses are either: White Faced Black Spanish, Black Minorca, or a Ancona.
Let us know when you figure it out.