Murdo Fraser is an MSP for Mid-Scotland & Fife.  He speaks for the Scottish Conservatives on Economy, Energy, Tourism & Land Reform, and is a former Deputy Leader of the Scottish Conservatives.

During the run up to the Scottish independence referendum last September, I remember being assured by various Scots Conservative grandees (those self-proclaimed electoral experts who would run a mile in the other direction if ever asked to go and knock on doors or talk to ordinary voters) that a No vote would mean the disappearance of the SNP as a viable political force.

According to their arguments, once Scotland’s place in the United Kingdom was secured, the SNP would limp off into history, and Scottish politics would revert to a “normal” left-right fight between Labour and Tory.

I was always sceptical of that view. My own feeling was that a Yes vote anywhere above 40 per cent would simply give the Nationalists more heart, and be used by them as a springboard for a potential re-run at some opportune point in the future.

And so it has proved, at least so far. As any observer of Scottish politics will have spotted, far from seeing the demise of the SNP, the No vote in the referendum has simply given them added impetus. Current opinion polls suggest that the SNP are on course to make sweeping gains at the General Election, mainly at Labour’s expense.

Lord Ashcroft’s recent polling suggests that even the safest Labour seats could fall to the SNP, with astonishing swings of 20 per cent or more. We might be on the verge of a major realignment of Scottish politics, but certainly not the one previously predicted.

There are worrying implications for the future of the United Kingdom should there be a sizeable block of SNP MPs in the Commons after May 7. Needless to say, the Scottish Conservatives, under Ruth Davidson, will be fighting hard to try and limit their advance.

But quite apart for the consequences for the UK Parliament, I worry that we as a party are not learning from the experience of the Scottish referendum, and what it might mean for the next referendum looming on the horizon – that on our membership of the European Union. If the experience in Scotland tells us anything, it is that we should be very worried.

There is real concern that the Conservative Party will be seriously divided by an EU In/Out referendum, with the leadership (presumably) generally in favour, but many backbenchers, and grassroots activists, campaigning against. There is bound to be bitterness in a hard-fought campaign. Whatever the result, the wounds will take a long time to heal.

It has already been commented elsewhere that there could be serious consequences for the future of the United Kingdom if the UK as a whole votes to leave the EU, but Scotland (or for that matter, Wales and/or Northern Ireland) vote to stay in. Certainly from a Scottish perspective, such an outcome would be seized on by the SNP, as a trigger for another independence referendum.

“Scotland is being ripped out of the EU against its wishes,” the Nats would shriek. The only way to secure Scotland’s place within the EU would be, they would claim, to separate from the UK and apply for separate EU membership. It would be a dangerous situation for the future of the United Kingdom, and one which the Conservative and Unionist Party needs to be alive to (although I would fear that there will be some who would regard losing Scotland as a price worth paying for exiting the EU).

But the implications of a vote to stay in the EU are potentially equally devastating, though this time not for the future of the United Kingdom, but for the Conservative Party. And this will be particularly the case in the event of a close margin, perhaps the 55-45 split we saw in the Scottish referendum.

The only major party campaigning on the side of an “Out” vote would (presumably) be UKIP. If the precedent of the Scottish referendum is anything to go by, we could expect a major surge in their support post the referendum, even if they were on the losing side.

And because of tensions within the Conservatives, both at parliamentary and grass roots level, there must be a prospect of many Tories leaving our party to join UKIP in that scenario – especially if a close campaign is characterised by even a fraction of the bitterness that was evident is Scotland in the months running up to last September’s vote.

A vote to stay in the EU, if sufficiently close, could lead to a major realignment of UK politics, with the anti-EU party being the major beneficiary. The Conservative tactic of trying to see off UKIP by pledging an EU referendum could backfire spectacularly, with our reduction as a significant political force.

We are, of course, in uncharted territory. No one can predict with any accuracy what might happen in the wake of an EU referendum, if indeed we ever have one. But all of us in the Conservative and Unionist Party need to be aware of the risks.

Could an EU referendum mean the end of the United Kingdom, or the end of the Conservative Party as we currently know it? The lesson of September’s referendum is that we need to be alive to both possibilities.