Archibald Primrose, 5th Earl of Rosebery
Rosebery resigned as leader of the Liberal Party in 1896, and gradually moved further and further from the mainstream of the party, supporting the Boer War and opposing Irish Home Rule, a position which prevented him from taking part in the Liberal government that returned to power in 1905.  In his later years, Rosebery turned to writing, including biographies of Lord Chatham, Pitt the Younger, Napoleon, and Lord Randolph Churchill.  He was also famous for his champion racehorses.