Question: Geoffrey G. Butler is the uncle and mentor of a man who was a prominent what? 
Sentence (from "Rab Butler"): He was one of his party's leaders in promoting the Post-war consensus through which the major parties largely agreed on the main points of domestic policy until the 1970s, sometimes known as "Butskellism" from an elision of his name with that of his Labour counterpart Hugh Gaitskell.
Relevant evidence: No