Jim is described as a "big good-looking blond giant of a man". He enjoys assembling model construction units, and is assembling a strato-cruiser while eating supper with Cherry. She tells him not to try to tell her that he bought that set as a Christmas present for his nephew, Michael, because she knows that he bought it so that he could play with it himself. Jim says that Michael is not quite old enough for it yet.
Jim also likes music, and says that one cannot listen to music with the vvolume turned down low, because you do not get the tone if you do not have the volume. At one point, he has a row with Mrs Hartwell, who lives next door, because she objected to him and Cherry having The Messiah on a bit loudly.
Later in the novel, Cherry asks Miss Marple if she and Jim could come and live in her house, in the rooms above the kitchen, as they are both fed up with their house in The Development. She says that if Jim could have the room above the stables, he would fix it up like new, and would be able to have all his construction models there. She also says that Jim could do plumbing or carpentry for Miss Marple.