Most opinion polls prior to the election had indicated a comfortable Labour victory and had put Labour up to 12.4% ahead of the Conservatives. On election day, however, a late swing gave the Conservatives a 3.4% lead.
The date of 18 June was supposedly chosen because Harold Wilson wanted to go to the polls before the introduction of decimal coinage in early 1971, for which his government had been responsible and which he thought was hugely unpopular and because Wilson sought to gain some momentum by surprising the Conservatives, who were expecting an October election.
Commentators believed that an unexpectedly bad set of balance of payments figures released in polling week, and loss of national prestige after the England football team's defeat in the World Cup, contributed to the Labour defeat.
Other factors that were cited as reasons for the Conservative victory included union indiscipline, rising prices, the risk of devaluation, the government’s imposition of Selective Employment Tax (SET) and a set of jobless figures released on polling day showing unemployment at its highest level since 1940. Interviewed by Robin Day, the outgoing Prime Minister Harold Wilson highlighted the possibility that “complacency engendered by the opinion polls” may have resulted in a poor turnout of Labour supporters. As defending world champions, England's venture in the World Cup attracted a much keener public interest than the general election did.
American pollster Douglas Schoen and Oxford University academic R. W. Johnson asserted that Enoch Powell had attracted 2.5 million votes to the Conservatives, although the Conservative vote only increased by 1.7 million. Johnson later stated "It became clear that Powell had won the 1970 election for the Tories...of all those who had switched their vote from one party to another, 50 per cent were working class Powellites". The Professor of Political Science Randall Hansen assessed a range of studies, including some which contended that Powell had made little or no difference to the result, but concluded that “At the very least, Powell's effect was likely to have fired up the Conservative vote in constituencies which would have voted Tory in any event”. Election night commentators Michael Barratt and Jeffrey Preece both dismissed any special ‘Powell factor’, as did Conservative MPs Reginald Maudling, Timothy Raison and Hugh Dykes.
This is the only occasion since the Second World War where a working majority for one party was transformed into a working majority for another party in the course of a single election.
The most notable casualty of the election was George Brown, Deputy Leader of the Labour Party, who lost to the Conservative candidate in the Belper constituency. Brown had held the seat since 1945.
Unusually for the Liberals the by-elections between 1966-1970 had proved fruitless, with many Liberal candidates losing deposits. The Liberals found themselves struggling to introduce their new leader Jeremy Thorpe to the public due to the extensive coverage and attention paid to Enoch Powell. The election result was poor for the Liberals, with Thorpe only narrowly winning his own seat in North Devon.
This was the first general election where 18 year olds had the right to vote. Therefore despite 1.1 million more people voting in 1970 compared to 1966, turnout actually fell by 3%. Labour's number of votes, 12.2 million, was ironically the same amount they had needed to win in 1964. The Tory vote surge cost Labour in many marginal seats. As for the Liberals a small 1% drop in their vote share saw them lose 6 seats, 3 of which were held by the narrowest of margins.
In the end the Conservatives achieved a swing of 4.7%, enough to give them a comfortable working majority. As for the smaller parties, they increased their number in the commons from 2 to 6 seats.