Yes, TriciaF, the Scottish Referendum was also advisory. I think that, if you are sincerely going to use a referendum to tell you the "settled will" of the people, then I think you need to make it conditional that the overall winning vote represents at least 50% of the electorate - which is not the same as 50% of those who cast a vote.
In the 1979 Devolution referendum, there was a 63% turnout, and the Yes vote was 51%, No 48%. On the face of it, therefore, the Yes vote won all those years ago. However, the condition was that at least 40% of the electorate had to vote yes, so the devolution bill was not carried.
In 2014: 55.3% of those who voted said No, 44.7% said Yes. That gives us a 10% majority for No, which in turn means that nationalists would need a swing of 5% between now and the next putative referendum, which they are already starting to campaign for.
But that’s not quite right. For a start, the turn-out was 84.59% of a total electorate of 4,283,392. This means that the Yes vote really captured just 37.78% of voters. That’s more than the 32.9% in 1979, when they captured 51.62% of the votes cast, but it’s still not much more than 1/3rd of the electorate. Turnout was lowest in the areas which returned an overall ‘Yes’. On the other hand, the ‘No’ only captured 46.7% of the vote — dramatically more than they got in 1979, when the total ‘No’ vote was 30.8%, but still not an outright majority. I think this gives a truer picture of "the will of the people".