Who is Paul Mason from Death in the Long Grass and what is their importance?

Paul Mason is one of Capstick's clients for an extended safari. One day, while Mason and Capstick were eating breakfast, they watched a woman walk by on her way to fish in the nearby river, where she is subsequently attacked and taken by a crocodile. Mason and Capstick arrived too late to do more than see the woman's arm wave feebly and go under. Mason is aghast at the spectacle and over the next several days focused on locating the gigantic crocodile, which they do.