However, senior SNP figures, including then First Minister Alex Salmond, said that the referendum would be a “once in a generation opportunity” for Scotland.

The Scottish Government’s 2013 white paper, Scotland’s Future, which made the case for Scottish independence, also defined the referendum as a “once in a generation opportunity”.

In the Q&A section of the document, The Scottish Government answers the question “If Scotland votes No, will there be another referendum on independence at a later date?”

The Scottish Government’s response was: “The Edinburgh Agreement states that a referendum must be held by the end of 2014. There is no arrangement in place for another referendum on independence.

“It is the view of the current Scottish Government that a referendum is a once-in-a-generation opportunity. This means that only a majority vote for Yes in 2014 would give certainty that Scotland will be independent.”

Before the 2014 vote, Nicola Sturgeon herself repeatedly called the referendum a “once in a lifetime” or “once in a generation” opportunity, such as in an interview with the BBC’s Daily Politics, where she said: “The SNP have always said that in our view these kind of referendums are ‘once in a generation’ events.”