Brexit brought out the worst in me, I’m the first to admit. As the empty chaos of Westminster politics revealed itself in the days following the vote, I ranted and raved with the best of them. In fact, I felt such a rush of despair in the immediate aftermath that I remember mumbling some pretty nasty stuff under my breath. Thankfully however, the worst of these insults were heard only by me; my brain’s internal filter instinctively knew they were not for public consumption.

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Which makes me think Alan Cumming’s internal filter must have suffered a serious malfunction. That’s the only excuse I can think of for the respected Scots actor making such ill-advised comments about English voters during an interview at the weekend. “I was appalled when I heard the result,” he told the Sunday Herald. “And I have three words to sum it up. Stupid. English. People.”

I expected better of Cumming, who is usually a thoughtful and intelligent presence both on and off stage. No matter how frustrated you may feel, calling ordinary folk of any nationality “stupid”, especially in public, is never a very good idea. This veteran supporter of Scottish independence should have known this.

The comments come at a time when Scotland is awash with talk of a second independence referendum. If nothing else, Cummings’ Brexit outburst should remind all those who support independence just how important it will be to strike the right tone if and when the time comes.

And as First Minister Nicola Sturgeon's keynote speech in Edinburgh today will make clear, it's now looking more and more like "when" as opposed to "if". Ms Sturgeon will lay down the five key Scottish areas of interests that she believes the Brexit vote puts at risk: democracy, the economy, social protection, solidarity and influence. She will make it clear that it is her intention to pursue every means possible of retaining these areas of interest for Scotland within the UK. But at the same time the First Minister knows that the neither the UK nor the EU will not be able to offer Scotland assurances on any of these things under Brexit. The options are bound to run out, Indyref2 is bound to come around.

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And, when it does, those supporting independence would be well-advised to swallow their pride and lay the ghost of Indyref 1 to rest. After all, this is a new moment in a whole new post-Brexit world; a second bite at the cherry will require the forging of new and unexpected alliances, and the ruthless rejection of existing ones that are no longer beneficial. A new, more realistic and relevant case will have to be formulated to persuade Scots of the merits of leaving post-Brexit Britain.

Despite the scary lack of stability and integrity at Westminster, the chaos that made the UK the laughing stock of the world, nothing can be taken for granted; Scottish independence is not inevitable. But it is possible, and on the cards. You sense a moment of both fear and exhilaration in the making.

But any new campaign will only succeed if it is disciplined enough to treat the electorate with respect. I say this in the face of the glut of irritatingly gleeful “I told you so” comments doing the rounds post-Brexit in some sections of the independence movement. There may or may not be elements of truth in such tropes, but smugness rarely goes down well, especially when the whole UK faces such potentially dire economic and social consequences as a result of Brexit. Surely a good dose of sensible humility will be more likely to win the day?

After all, it would be a mistake to believe disillusionment with Westminster means independence will be easier to sell second time around. Granted, many who voted No in 2014 have already indicated a change of heart. Whether they will feel the same once the shock of Brexit has worn off, once the chaos of the immediate aftermath is forgotten, remains to be seen.

This is perhaps where the new alliances come in. We’ve already seen polls over the past couple of weeks suggesting the vast majority of Europe would welcome an independent Scotland into the EU. Another new alliance, meanwhile, could be the financial services industry that was so opposed to independence in 2014; talk of Edinburgh becoming a post-Brexit hub has been doing the rounds as far afield as Paris, Frankfurt and Luxembourg.

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These relationships will require delicate handling and cultivation. So, too, will any re-booted relationship between a new independence campaign and the Scottish people. The stakes could not be higher, which means the tone must be pitch perfect. Perhaps Alan Cumming would be advised to keep his head down this time around.