I saw this bird while walking round the lake in Llandrindod Wells earlier in the year (I just found the phots I took that day but never posted). I'm pretty sure it's a blackbird but there seems to be a problem with pigmentation.
What an interesting specimen you've caught here. I have heard of leucism before but did not realize that it could cause patchy loss of pigment like this. He is quite a handsome bird and you've got that nice focus on his eye too.
