Arthur James Balfour 1st Earl of Balfour KG OM PC FRS FBA DL was a British statesman of the Conservative Party who served as Prime Minister of the United Kingdom from 1902 to 1905. Arthur James Balfour 1st Earl of Balfour KG OM PC FRS FBA DL was a British statesman of the Conservative Party who served as Prime Minister of the United Kingdom from 1902 to 1905.