A black and white movie. Story about 2 antiquarians situated opposite each other in a little road - perhaps in London. One has more modern articles - the other ancient. They have always been at war - but at Christmas one of them becomes ill and the other helps. They end up celebrating Christmas together and as a gift they give each other the last Chess piece they each lack for a complete collection on their Chess board. It is an English movie with English lead actors of the time. Perhaps from 1970 or early 1980's. Can you help me?