He had an Oxonian accent.
In 2275, as a lieutenant aboard the Enterprise, Heming served as an apprentice navigator under Pavel Chekov, with Chekov taking the helm, during testing of a prototype inversion drive. Following one jump, Heming's face was pale, but he reported success, calculating that Rigel was 100,800 light years away and that the ship was 101,120 light years from the Lesser Magellanic Cloud. (TOS novel: The Wounded Sky)
In 2285, while serving aboard the Excelsior, Heming's leg was treated in sickbay, and afterward it felt much better. Leonard McCoy saw Heming in the mess hall and asked him to drop by so the leg could be rechecked. (TOS comic: "The Last Word")