Let’s assume for a second that you want to stop Brexit, or at the very least, stop Boris Johnson’s version of Brexit. How do you do it? Jeremy Corbyn is currently eating Tory dust in the polls, the Liberal Democrats – despite Jo Swinson’s continued fever dream protests – stand a one in never-fucking-going-to-happen chance of winning a majority, and the two refuse to co-operate. So what’s a disenfranchised voter to do?

According to some, tactical voting (i.e. backing the candidate most likely to defeat the Tories, regardless of your political affiliation) is the only way forward, but much like attempting to count the number of Boris’ offspring, it’s a tall and mystifying task.

There are at least five websites (“three remain organisations and two groups of nerds”, according to political blogger and analyst Jon Worth) that are analysing voting records, opinion polls and other data to give voters advice. But wouldn’t it be lovely to have cold, hard proof that tactical voting can not only work, but push the Tories to near-wipeout?

But wait! Cast your mind back to 1997. You know, the year that Labour absolutely boyed the Tories with the biggest majority since World War II? Anybody under the age of 40 won’t have been old enough to vote back then so they might not remember the specifics – such as the fact that the Tory wipe-out was partially credited to GROT (Get Rid Of Them), Britain’s first nationwide tactical voting campaign.

“GROT came out of the conviction we had that the if the anti-Tory vote was split [between Labour and the Liberal Democrats] we would have the Tories – and nuclear weapons – for the long future," explains Bruce Kent, the peace activist who spearheaded the campaign.

Bruce and his team circulated a list of about 90 constituencies where tactical voting could make a difference – and remember, this was a good decade before Twitter, when so few people had the internet at home that officials hadn’t even bothered to count their numbers.

"It was a small effort run by a handful, certainly less than ten, with no funds, but we did have an effect,” Bruce added. “All but one of our GROT seats produced someone other than Tory.”

A 2015 study into the effects of tactical voting on the 1997 election said that Labour might not have won nine of its seats were it not for Liberal Democrats supporters who switched allegiances temporarily. Similarly, 21 of the 46 Lib Dem seats won in 1997 were likely as a result of votes lent by Labourites.

Dr Michael Hermann, one of the study’s authors, said that the Liberal Democrats could benefit from tactical voting again in the 2019 election.

“What both elections seem to have in common, from my point of view, is a large group of voters who strongly dislike the incumbent Tory government, and for whom it might thus make sense to vote tactically in order to avoid a Tory victory in their seat,” he told VICE.

"The biggest difference seems to be voter alignment. In 1997, voters followed the traditional left-right divide [switching from left to centre, centre to left, or centre to right] but the issue of Brexit adds another layer to the picture.

”This may open up or even block avenues for tactical switching, depending on how strongly potential tactical voters care about these issues. Labour supporters who support Brexit might tactically switch to Conservative, and Liberal Democrat supporters might not switch to Labour because of their unclear Brexit position.”

Worth, a British-born overseas voter who lives in Berlin, warns that it’s this inter-remain split that could frustrate tactical voting efforts.

"It works best in constituencies which are against Brexit where you have the Conservatives in first place and you have one of the anti-Brexit parties – be that Labour, the Liberals, or indeed the SNP or Plaid Cymru if you're in Wales or Scotland – in second,” he told VICE.

“But when it becomes difficult is when you have two or three remain parties that refuse to collaborate. If you've got a three-way marginal between the Conservatives, the Liberal Democrats and Labour, it becomes an even harder coordination task."

According to Gina Miller, the businesswoman and campaigner behind the Remain United tactical voting site, “to wipe out a Tory majority we need more than 6.5 million to tactically vote”. This might sound like a lot, but it’s the exact number thought to have vote-switched in the 2017 general election, according to Electoral Reform Society estimates.

“We know that tactical voting had an impact in 2017,” Worth added. “Will it be enough to to keep pro-Brexit parties out this time? I don't know yet.”

Whereas tactical voting helped deliver a clear, decisive majority in 1997, it failed to do so in 2017 and, according to Worth, is unlikely to do so again this time around.

“I see the chances that Labour would have enough seats to govern on its own as next to impossible,” he said, meaning that Corbyn would need to make alliances in order to become Prime Minister.

So far, Jo Swinson has told the Financial Times that she would “rather go into another election than see Boris Johnson or Jeremy Corbyn in that position [of prime minister] as a result of Lib Dem votes”. However, Holt thinks that Swinson has left herself “a degree of wiggle room”, and could still “temporarily support” a minority Labour government in order to obtain a second EU referendum.

“There is another permutation, which might be that Labour has enough seats together with the SNP and doesn’t need the Liberal Democrats at all, but even that is a hell of a long shot,” he said. "Basically, if all of the pro-remain parties end up with enough seats to deny the Tories a majority, you’ll still end up with a very messy scenario that could probably just about agreed to hold a second referendum but would agree about practically nothing else. It's not an ideal scenario by any means, but if you're pro-remain, that's still better than having a Boris Johnson government.”

Kent echoed this, acknowledging that “the average voter is in a muddle”.