I'm looking for an old movie I saw part of on TCM Friday 9/27/13. It is set in post WWII England and features an American Army officer who rents hunting land in a rural area and accidentally shoots a man he supposes to be a poacher. The dead man is actually shot by someone else. There is a spy element in the plot as well. I think the first name of the lead actor is William, but I'm not certain of that.