With a larger pro-independence majority at Holyrood following the Scottish Parliament election, the argument over a second referendum has intensified.
Since the SNP’s historic victory, granting First Minister Nicola Sturgeon’s party a fourth consecutive term in office, Boris Johnson has said that focus should be on the UK’s recovery from the Covid crisis and not on “indyref2”.
Increased debate on the matter of whether the country should remain a part of the UK has thrust the first referendum in 2014 - and its result - back into the spotlight.
Here is everything you need to know about the first Scottish independence referendum.
Why was there an independence referendum in 2014?
The SNP won the Holyrood election in 2011 with an outright majority of 69 seats, confounding pollsters.
The party’s campaign was based around holding an independence referendum and giving Scots a choice about their country’s future.
Former First Minister Alex Salmond said at the time that he had gained the “moral authority” to deliver a vote within the next five years.
Based on the party’s landslide victory, the Prime Minister, David Cameron, agreed that Scotland should be able to hold a referendum about splitting off from the rest of the UK.
Powers were then transferred from Westminster to allow the Scottish Parliament to legislate for the vote.
This happened through the Referendum Agreement, which was signed by Mr Cameron and Mr Salmond on 15 October 2012.
What was the outcome of the vote?
More than three and a half million people in Scotland had their say on the future of the country on Thursday 18 September 2014.
Anyone over the age of 16 was permitted to vote in the referendum, for the first time in the history of the UK.
Voters were asked the question: “Should Scotland be an independent country?” and were given the option of a “Yes” or “No” answer.
Unfortunately for pro-independence supporters, the “No” campaign won with 2,001,926 votes over the “Yes” camp’s 1,617,989.
The outcome was split by 55.3 per cent to 44.7 per cent, with the majority of voters choosing that Scotland remained part of the UK.
Both sides told voters that it was a “once in a generation” opportunity.
Why does the SNP still want independence?
The issue of Scottish independence was thrown into the limelight once again following the 2016 Brexit vote.
While the UK as a whole voted to leave the EU by 52 per cent to 48 per cent, Scottish voters backed the Remain camp by an overwhelming 62 per cent to 38 per cent.
After the UK voted Leave, Nicola Sturgeon and the SNP began pushing for another referendum, or “indyref2”.
The argument was that Scotland should be able to take its future into its own hands, rather than being forced to leave the EU “against its will” by the UK’s Conservative government.
The SNP also claim that independence would allow Scotland to rejoin the EU in future.
However, Brexit isn’t the be-all-and-end-all when it comes down to the reasons Scots want independence.
The UK Government’s handling of the coronavirus crisis has also bolstered support for independence among Scots, with many feeling the Scottish Government led the response to the pandemic better than Mr Johnson’s cabinet.
Other proponents of independence draw heavily on the argument for self-determination - that Scotland is a distinct nation from the UK and should control its full political authority.
Scotland has also traditionally sat further left than England on the political spectrum, meaning many Scots feel disillusioned by the current Conservative government and its policies.
Furthermore, the SNP is vigorously opposed to nuclear weapons in Scotland, and the UK’s nuclear deterrent is stationed at the Faslane naval base.
Have opinion polls changed since 2014?
Since the 2014 vote, and Brexit, a lot has changed in terms of public opinion on Scottish independence.
Since the middle of 2020, according to the New Statesman poll tracker, a consistent majority of Scots have backed leaving the UK.
But more recently there seems to be increased momentum on the “No” side.
A Savanta ComRes poll on the latest voting intentions on the question of independence carried out on 4 May 2021 predicted a 42 per cent “Yes” vote and a 50 per cent “No” vote, giving the latter side a lead of eight points.
However, an Opinium poll the day before suggested a tie of 45 per cent between the two sides.
And a Panelbase poll undertaken at the end of April saw a lead of three points for “Yes” at 48 per cent to 45.
Will there be another referendum?
Nicola Sturgeon has said it is a “matter of when, not if” there will be another vote on Scottish independence.
While the SNP has vowed to push for a second referendum, Boris Johnson has said he would block another vote.
But timing is crucial, and Ms Sturgeon has said she would not propose an immediate vote while the country is in recovery from Covid.
Instead, the SNP has said it intends the vote to be held within the first half of the next five-year term - so another referendum could happen by the end of 2023.
However, under the 1998 Scotland Act, all matters relating to the "Union of the Kingdoms of Scotland and England" are reserved to Westminster.
Mr Johnson’s government would have to grant the Scottish Government the authority to hold a fresh vote using a “Section 30” order.
The Conservatives argue that that gives them the authority on whether or not Scotland gets to hold a referendum.
Any legislation introduced by the SNP for another vote could be challenged by the UK Government in court.
But Ms Sturgeon has said the Prime Minister would be blocking Scottish democracy, and the will of the people, if he did not allow one to go ahead.
In a recent phone call with Mr Johnson, the SNP leader told him that another referendum was inevitable once Covid recovery had gotten underway.
Her spokesman said: "The First Minister made clear that her immediate focus was on steering the country through Covid and into recovery, and that a newly elected Scottish Government would work with the UK Government as far as possible on that aim.
"The First Minister also reiterated her intention to ensure that the people of Scotland can choose our own future when the crisis is over, and made clear that the question of a referendum is now a matter of when, not if."