Makes sense - kind of like how the former king of Bulgaria managed to get himself elected PM sixty years down the line (only less spectacular, I suppose ). See link - the Marquess of Hartington, future Duke of Devonshire, was Secretary for War at that point, but held his seat in the Commons until he became Duke. And Lord Randolph Churchill (Winston's father) is just styled "Lord" as you can see - according to Wikipedia, he was the third son of the Duke of Marlborough, hence never got a peerage or seat in the Lords, not even a courtesy title, but he still got to call himself Lord.