The portrayal of (possibly faked or real) arm amputees in movies matters. So I went through my DVD copy of this movie slowly to check this one out. And lo and behold we see a BECKER hand.
It appears to be mounted on a pin lock / silicone liner type arm as the white plastic button of what appears to be an Icelock seems to be visible. Socket and hand have been painted black or dark brown.
But, check for yourself.
Images (C) Copyright by Winchester Films, BBC Films and Mandate Pictures
Really well done.