While serving briefly as Chancellor of the Exchequer before becoming premier, Major had persuaded Margaret Thatcher to allow the Pound to join the Exchange Rate Mechanism (ERM) – the forerunner of the euro. In September 1992, just five months after the election victory, the Pound was forced out of the ERM. In reaction, the Conservative Party became more euro-sceptic and less-disciplined, its economic policy had to be re-written and Major's reputation sank.
Despite vigorous and visible attempts to control his party (including Major’s resorting to resigning and re-contesting the leadership) the Conservative majority in Parliament leaked away, leaving Major running a minority government as he limped towards defeat in 1997.
Four Conservative MPs died and their seats were won by Liberal Democrats in by-elections (Newbury, Christchurch, Eastleigh and Littleborough & Saddleworth). Four others died and their seats were won by other parties (Dudley West, Staffordshire South East and Wirral South by Labour, Perth & Kinross by the SNP).
Two Conservative MPs defected to the Liberal Democrats (Emma Nicholson and Peter Thurnham). Alan Howarth defected from the Conservatives to Labour and George Gardiner defected to the Referendum Party. If the four defectors had remained in the party, the Conservatives would still have held a fragile majority in parliament.
After his election victory, David Cameron must be wondering what could possibly go wrong?