Who is Jock Grant-Menzies from A Handful of Dust and what is their importance?

Jock Grant-Menzies is a friend of Tony Last. He holds a representative position in the government, noted by the speech on pigs that he has been planning the entire novel. He is attractive to the women characters in the novel and is a wanted commodity. Jock and Tony become closer friends when Brenda starts having an affair. He clearly doesn't approve of how she is treating Tony. Nonetheless, he marries Brenda once Tony dies.