Who is Peter Hankin and Joe Joubert from Death in the Long Grass and what is their importance?

Peter Hankin was a professional African hunter. He operated a hunting concession which bordered the one operated by Capstick. After a long and successful hunting career, Hankin led a group of photographers into a nature preserve where rifles were prohibited. While there, he was subsequently attacked, killed, and partially eaten by a lion. Joe Joubert, a professional hunter on Hankin's staff, tracked and killed the man-eating lion the next day.