2019 marks a major milestone in the history of devolution for it was twenty years ago that the modern Scottish Parliament first convened. Prior to the referendum which delivered that Parliament, Labour’s then Shadow Secretary of State for Scotland, George Robertson, proclaimed that devolution would ‘kill nationalism stone dead’ and would represent the settled will of the Scottish people. Fast forward two decades and an SNP First Minister – at the head of a government which has been in power for 12 years – this week set out her plans for a second referendum on Scottish independence, telling MSPs that Scots must be given a choice between Brexit Britain and a future as a ‘modern European nation’. The rise of the SNP may have been the story of the first chapter of devolution, but what are the chances independence will the defining moment of the second? And with the UK Government pledging to block any vote, will there even be a second referendum at all?

Nicola Sturgeon, who has the unenviable task of juggling public opinion with her restless party base, stated this week that her preference is to hold a second referendum before 2021, the end of this Scottish Parliamentary term. Within 24 hours the UK Government, as expected, said it would not countenance devolving the legal powers to allow this to happen. Regardless, the Scottish Government has pledged to press ahead with the introduction of a ‘Framework Bill’, which aims to set the rules for any future referendum. Critically though, this legally disputed Bill cannot legislate for a binding vote. That requires the transfer of a Section 30 Order, the part of the Scotland Act which allows the devolved Government to legislate in a reserved area, and with this not forthcoming the UK and Scottish Governments find themselves, once more, at an impasse.

The UK Government’s refusal to transfer a Section 30 Order will have come as no surprise to the SNP leadership. Theresa May refused to do so in 2017 and Nicola Sturgeon fully anticipated her doing so this time. On paper it may appear that this renders Indyref2 dead before it even gets off the ground. However, Nicola Sturgeon is prepared to play the long game, and there is one critical moment she hopes will put her mandate beyond any doubt; the 2021 Scottish Parliament election.

Whether a cunning strategy or a cynical move to kick the can down the road due to polling which stubbornly remains in favour of the UK, the First Minister’s plan is to make the next election a referendum on a referendum. Should the SNP and the pro-independence Green Party retain their majority in the Holyrood Parliament, having run on an explicit promise to deliver a referendum, Sturgeon will claim a cast-iron mandate to hold a second plebiscite. Privately even the Scottish Conservative Party acknowledges that in these circumstances, it would be very difficult for the UK Government to stand in the way. Should the pro-Union parties – the Conservatives, Labour and the Liberal Democrats – have a combined majority in Holyrood post-2021, even in the likely event the SNP heads up a minority Government, then independence will be off the table as a serious prospect for a decade, perhaps longer. For a party which has campaigned for independence for close to a century, the stakes could not be higher.

The Framework Bill the Scottish Government is to introduce to Holyrood, therefore, is not a clumsy attempt to legislate for a referendum which is doomed to fail; rather it is intended to project a sense of momentum. This, along with the Citizens’ Assembly the SNP has vowed to establish, is part of the strategy to ensure the 2021 election is an independence election. Unofficially, the second referendum campaign has already begun.

Debate is already raging over the fundamentals of Scottish independence in a post-Brexit (if indeed that does happen) era. This weekend the SNP will ask party members to officially sanction the policy of adopting a new Scottish currency tied to a newly established independent central bank. Meanwhile opponents of independence point to the fact that a border between Scotland and England will likely need to be erected in the hypothetical case of a future independent Scotland rejoining the EU.

This debate is set to dominate political discourse in Scotland over the next 18 months. Whilst inextricably linked to Brexit, Scotland’s national question is one of UK membership, not necessarily European membership. Polls still suggest that the majority of Scots favour the UK, and in many ways the Brexit chaos has served to reinforce how difficult it is for a nation to leave a deeply integrated political and economic union. The SNP, however, are no strangers to being the underdog and, having secured 45% of the vote in 2014 despite starting on a lowly 28%, they believe they can now convince the majority of Scots that independence is the best path for the country.

This summer MSPs and MPs will come together to celebrate twenty years of the Scottish Parliament. The 2021 election is set to be the most important yet.