A mad chaffinch at the window

I think that it is fairly well known that Britain's cheerful robin isn't perhaps such a nice character after all. Well certainly he can be very aggressive if he thinks another robin is invading his patch and I've heard of them attacking their own reflections in a window say.

Not just robins it seems because I've had a male chaffinch flying at a small window on the first floor at the back of my cottage. Good job his beak is strong because he has been hitting the glass with some force. This behaviour has been repeated at one or two of my neighbour's windows and I can only assume that it his reflection he has been attacking so vigorously! I have a blind for that window which I am keeping lowered at the moment in the hope that the poor demented chap will give up! So far this morning peace reigns .......