On May 7 David Cameron returned to Downing Street with more seats and a higher share of the national vote than in 2010. That was a remarkable double achievement for an incumbent Prime Minister after a significant period in power.
Harold Macmillan increased his majority at the 1959 election, but with a slightly lower share of the vote. Over half a century earlier Lord Salisbury achieved a higher share of the vote at the 1900 election, but his majority was slightly reduced.
Anthony Eden achieved both a larger majority and a higher proportion of the vote at the 1955 election, but he had the advantage of being a new Prime Minister, appointed only weeks before the election.
Only one well-established Prime Minister before David Cameron has achieved both more seats and increased vote share. That was Lord Palmerston in 1857, long before the introduction of universal suffrage.