Who is Patrick (Mac) MacDowell from The Eye in the Door and what is their importance?

Patrick MacDowell is one of Billy Prior's childhood friends from Salford. Mac's mother, Lizzie, was a heavy drinker and a known prostitute. For much of his childhood, Mac was severely neglected by his mother. Consequently, Mac was eventually taken in by Beattie Roper. Mac's sentiments against the war lead to his being on the run from the authorities. As a conscientious objector, Mac faces prison time if he is caught. Once detained, the only option Mac has is to remain in prison or to put on an army uniform. Mac views the war as the government's betrayal of the common man. He believes that sending young British men to die at the Front against their will is unconscionable. When he and Billy Prior meet at the cattle pens, Mac realizes that although he and Billy had once been close, their friendship will never be the same.