Since Britain first joined the EU in 1973, the balance has constantly shifted between those in favor of membership and those who want to leave.
The public was initially divided on the issue when the Conservative government first led Britain into the EU’s predecessor, the European Economic Community. There was a dramatic swing in public opinion by the 1975 referendum, with two-thirds of voters opting to stay in the EU.
The polling firm Ipsos MORI, then just MORI, began tracking public opinion on the EU shortly after the referendum. By 1979, it became clear that voters had begun to regret their 1975 decision—60% said they would vote to leave the EU if another referendum was called, while only 32% said they would stay.
Public opinion to leave the EU in what’s now called a ”Brexit” peaked in 1980, when the Conservative Margaret Thatcher was in power, with 65% keen to leave. Then Thatcher was able to renegotiate Britain’s membership to the EU, which pushed public opinion toward staying in. By 1987, 47% wanted to say and 39% wanted to leave.
From the 1990s, those wanting to stay in had a comfortable majority in public opinion polls, though the leave camp would get a narrow majority every now and then. Most of Ipsos MORI’s polling from the 2015 general election to May 2016 showed Britons favoring staying in the EU, but the most recent poll had “leave” back in the lead.
With less than a day before the nation votes in another referendum, experts suggest the results are far too close to call. Public opinion appears as evenly divided now as it was in the early 1970s.