Metal Plaque of Churchill in Relief C. 1945

This large metal plaque is made of solidly cast metal and weighs an absolute ton. I am not sure what it is made of, but it could be solid brass that was sliver plated. The back looks as if there could be brass underneath. The front looks as if some of the plating had come off where it had been too vigorously cleaned in the past. It measures 25 cm x 19 cm and the back part, that is not in relief, is about 10 mm thick. Please add R48 for postage.