Nicola Sturgeon is predicting an "almost certain" drive for another independence referendum if Scotland votes to stay in the European Union (EU) but England votes to leave.

This prospect will undoubtedly be at the back of voters' minds as they go to the polls to elect their next batch of MSPs next month, with the EU referendum looming just seven weeks later.

With all of Scotland's major parties firmly in the Remain camp, there has been little argument between them, leaving them free to focus on crucial issues of taxation and spending in Scotland.

Parties south of the border seem to have caught the referendum bug that infected Scotland in 2014 where Leave or Remain have become "proxies" for policies - principally immigration, national sovereignty and foreign affairs.

This has subsequently brought to the fore some of the powers Holyrood does not currently hold but which the nationalists say they would manage differently.

For nationalists a Brexit could represent the next big push towards independence, and for unionists it will be all the more reason to back a pro-UK party.

Ms Sturgeon has stressed she is not in favour of a Brexit under any circumstances - she wants an independent Scotland in the EU side-by-side with its closest neighbour.

This is despite polls showing a Brexit could push support for independence into a slight majority, but it is unclear how Scots would react once the realities sink in.

Even a swift post-Brexit IndyRef2 would take time to arrange, giving voters pause to adjust to the new political reality and weigh up the implications of foresaking a neighbouring union to assert your attachment to a more geographically distant one.

English reaction to a Brexit could be crucial in saving or breaking the union - particularly if it leads to a rise in English nationalism that is already being felt in the rising support for Ukip and the drive for English-votes-for-English-laws.

Christine O'Neill, chairman of Brodies, a specialist in constitutional law and former adviser to Holyrood's Devolution (Further Powers) Committee, said: "I think that many people would see the referendum on EU membership as being about a debate over relatively discrete policy issues - principally the UK's approach to inward migration from inside and outside the EU - more than a debate about broader questions about national identity, the internal market or the legitimacy of EU institutions".