Who is Len and Jean Harvey, Willy De Beer, and Colin Matthews from Death in the Long Grass and what is their importance?

Len and Jean Harvey, Willy De Beer, and Colin Matthews are attacked one night by a single lion which kills Len, seriously injured Willy and Colin, and injures Jean. Len and Jean stayed with Willy De Beer while on their honeymoon, sleeping in a cabin near the De Beer's main house. Colin was staying with the family. One night, a lioness leapt through the cabin window and attacked Jean. Len responded by attacking the lioness with his bare hands, driving her away from Jean, before being killed and partially devoured. Summoned from the house, Willy and Colin approached the cabin with rifles. Willy looked through an open window and was attacked; the lioness nearly scalped him and threw him to the ground. The lioness then attacked and severely injured Colin while Willy gained his feet and, firing by sound along, shot the lion off Colin. At the time of the writing, Willy and Colin were expected to survive their injuries, including the loss of Colin's hand. Jean recovered completely.