If you needed proof of the value of legends in politics, just look at Jeremy Corbyn and the Labour Party.

For a period of 34 years that only ended last Thursday, we “knew” that the Labour party could never succeed at a general election with a radical left manifesto. The reason for our certainty was that Labour decided to accept the story that was told about how it lost the 1983 election – its manifesto that year was the “longest suicide note in history”, and the party was only later able to win back the trust of the British people by borrowing more and more Tory policies.

The countless other plausible reasons for the scale of the 1983 defeat – the shambolic and under-funded Labour campaign operation, the unusual split in the progressive vote brought about by the SDP/Liberal Alliance, the status of Margaret Thatcher as a victorious war leader – were all largely discounted. If it hadn’t been for the peculiar chain of events that led to the “totally unelectable” Jeremy Corbyn becoming Labour leader two years ago, we probably would never have discovered that the legend of 1983 is complete hogwash, and that left-wing policies can actually be rather popular in a general election after all.

The SNP currently stand at a 1983-style crossroads where they may be in danger of creating their own debilitating legend which could take decades to recover from. That seems an odd thing to say given that they won the general election in Scotland by a handsome margin – they were on the right end of a Thatcher-type landslide, not on the wrong end. The SNP victory was the rough equivalent of an overall majority of 120 at UK-wide level. Nevertheless, some in the party have lost a degree of perspective due to the undeniable shock of losing seats held by political giants such as Angus Robertson and Alex Salmond. One or two siren voices have started arguing that the SNP will never “recover” from its… well, from its victory, until it “listens to voters” and jettisons the policy of holding an independence referendum at the end of the Brexit process. This would be the rough equivalent of Labour’s about-turn in the years following 1983, when it abandoned some of its most fundamental beliefs, such as unilateral nuclear disarmament.

It’s unclear how much traction these voices will have. Nicola Sturgeon has promised to “reflect” on the reasons for losing constituencies such as Gordon and Moray, but so far hasn’t gone any further than that. In my view, though, it would be a strategic error of epic proportions to abandon the referendum policy. To understand why, simply consider the story that the SNP’s referendum-sceptics are telling the party: “We know that there isn’t going to be a referendum any time soon, because Theresa May won’t allow it, so we need to stop taking a hit for something that isn’t going to happen anyway.” Now imagine how that story, if accepted by Nicola Sturgeon, will be converted into unionist legend over the coming years: “The SNP demanded a referendum, but for the first time, a British Prime Minister actually stood up to them. The people of Scotland rose up to support the British government, and the SNP were forced to back down.”

Nonsense-on-stilts though it would be, that legend would drive a stake through the heart of the SNP’s strategy for achieving independence, regardless of whether the final push occurs at the end of the Brexit process, or in ten years’ time, or in twenty. Their expectation has always been that they would win a Scottish Parliament election on a manifesto commitment to hold an independence referendum, that the Scottish Parliament would formally give its backing to the plan, and that it would then be democratically unsustainable for the UK government to stand in the way. Well, the first two of those steps have occurred. If the party now collapses in fright and decides that they just have to pragmatically accept that the British Prime Minister can get away with saying “No” even after the immaculate democratic process that has taken place, they will be needlessly setting a horrendous precedent that could make it impossible to secure independence at any point over the coming decades.

Such a show of weakness might be understandable if the SNP had just been defeated at the ballot box. But to go down that road immediately after securing a landslide victory is much more dangerous, because it implicitly concedes that the party does not merely need to win elections to be able to insist upon a referendum – they instead need to win by a mind-bogglingly overwhelming margin. A key part of the legend will be that, because certain parts of Scotland (such as Aberdeenshire and the Borders) demonstrated their opposition to a referendum last week, that was tantamount to “Scotland saying No”. In other words, there is a minority veto. That principle simply cannot be accepted, because it would set a frighteningly high hurdle for the party to clear in future.

Jeremy Corbyn has proved that legends mean nothing in politics. History is constantly being rewritten.

There are undoubtedly sharp differences of opinion within the SNP on the best time to seek a mandate for independence. But logically, one thing that ought to unite all strands of opinion is that Nicola Sturgeon should stand her ground by insisting that the mandate that already exists for a referendum must be respected. If by any chance a referendum does not happen at the end of the Brexit process, it must be clearly seen that it was the UK government that stood in the way of democracy. If the SNP are instead seen to back down in the face of a defeat that didn’t actually happen, they would be self-inflicting a wound that might never properly heal.

James Kelly's blog, Scot goes POP!, is among the most popular political blogs in the UK. He has also contributed to a number of newspapers and magazines.

You can check out the blog here or follow James on Twitter.

James has also written for us about the tyranny of Theresa May, the madness of King Trump, the crisis created by the Brexit legal challenge and why Scottish Labour care more about Corbyn than their country.