It was one of the great political upsets of British post-War history.
In 1970, Britain's Labour Prime Minister, Harold Wilson, was widely expected to hold on to power in a general election he himself had called.
But when the voting verdict came in, Mr Wilson found himself being bundled out of Downing Street, and the Conservative leader, Edward Heath, taking his place.
And some sought solace in a simple explanation: football.
England had lost a World Cup quarter-final tie just four days before the vote, and this was no ordinary match.
Defeat had come at the hands of West Germany, the team England had beaten just four years previously to win the World Cup.
And right up until the end of the game, another England victory had seemed on the cards, with the side 2-0 up at half-time.
But then three German goals came in, one after the other.
"The sense of letdown could not have been greater," says Kier Radnedge, who watched the game as a young football reporter.
He believes it may well have affected the way some people then voted.
"It deflated the mood in the nation," he says, "therefore, they looked for something new. Something new in that case was voting in a new government."
Forty-six years later, the people of Britain will once again be voting in the wake of an international football tie, and that vote could prove more crucial than any individual election.
A referendum will decide whether or not the UK should remain a member of the European Union.
But just days beforehand, England, Wales and Northern Ireland will play the last of their group matches in the Euro 2016 championships.
Key European dates
- Saturday, 11 June: Wales v Slovakia; England v Russia
- Sunday, 12 June: Poland v Northern Ireland
- Thursday, 16 June: England v Wales; Ukraine v Northern Ireland
- Monday, 20 June: Russia v Wales; Slovakia v England
- Tuesday, 21 June: Northern Ireland v Germany
- Thursday 23 June: UK referendum
"If England, Wales or Northern Ireland have won their group, then it will make people feel good about being part of Europe," says Mark Perryman, founder of the company Football Philosophy.
"If they come home early, people will ask, 'Do we really want to part of this continent?'"
Campaigning in the referendum will not revolve around footballing matters, of course.
Debate on EU membership has tended to focus on economic issues, particularly whether a Britain out of the EU would be able to trade as easily with EU member states.
Also crucial is immigration, opponents of the EU saying membership allows too many foreigners to live and work in Britain.
Supporters, by contrast, say foreign workers have been a benefit to the UK, not a cost.
But Mr Radnedge says too much credence is given to rationality in political argument.
"People are swayed by their moods," he says about voting.
"It really is a lot to do with how people are feeling on the day."
Mr Radnedge admits the effects of a football match would be marginal, but then marginal votes count in what may be a close-run contest.
"It is illogical, but then people are illogical," he says.
Whoever wins or loses, the European Championships will certainly compete with the referendum campaign for space on newspaper front pages, and on radio and television news bulletins.
And that is not good for the government in this case, according to a former government spin doctor.
Charlie Whelan, who served as the press man for Gordon Brown when he was Britain's Chancellor of the Exchequer, says they always avoided any political event clashing with a major football tie.
"You want to control the news agenda as much as you can," Mr Whelan says.
"If you have no idea what's going to happen on any given day, the agenda is set by 22 guys kicking round a football."
But the clash of ballot and ball this June will not represent a completely new mixing of two otherwise-separate fields, because football has always provided an outlet for nationalist passions, and therefore raised questions of nationhood and national identity.
The rise of English nationalism was illustrated by England supporters starting to wave the flag of St George, rather than the Union Jack.
And the presence of so many European players in British club teams has made supporters question whether they want the best team money can buy, or whether instead fewer foreigners should be allowed on board, in order to nurture more native talent.
"Football clubs are the most European institutions [in Britain]," Mr Perryman says, "their players, the managers, the owners, the sponsors. Do supporters like that? Yes - but only if their team is winning."
For more on this story listen to Paul Moss's report on The World Tonight.