Walpole, Sir RobertWal‧pole, Sir Rob‧ert /ˈwɔːlpəʊl, ˈrɒbət $ ˈrɑːbərt/(1676–1745) a British politician in the whig party, who is usually regarded as the first British prime minister, a position which did not previously exist, and which he held from 1721 to 1742