IAN Blackford admits he is a reluctant leader.

The 56-year-old politician relaxes in his new oak-lined office at Westminster, once the retreat of the man he famously defeated in 2015 for the Highland seat of Ross, Skye and Lochaber; Charles Kennedy, who, as leader of the Liberal Democrats, occupied the same suite of offices as head of Britain’s third party.

Despite the political whirlwind of the last month, the Nationalist leader has a confession: he is actually enjoying the newfound role he never expected to have.

“I didn’t put myself forward for this. It was colleagues who encouraged me to stand. I had never given any thought about standing for the leadership,” he declares.

So he is a reluctant leader? “Yes, in that sense I was. But I’m very much enjoying the challenge and I will do the best to make sure we are an effective group in Westminster and working closely with our colleagues in government in Edinburgh.”

Very on message. But then again Nationalist MPs rarely, if ever, stray from the party line. An SNP MP has never defied the party whip; hence the critics’ complaint that the Nationalists are ruled by a Stalinist rod of iron.

The party leader smiles. “We impose discipline on ourselves. There is a unity of purpose as a parliamentary group…We thrash things out as a group and come to a settled position. You can’t impose discipline on a group of 35,” he insists. Clearly, you can, I suggest.

He recalls: “There was one famous occasion where one MP got confused in terms of where he should have been.”

This was in 2015 when the Western Isles MP Angus Brendan MacNeil, to his embarrassment, found himself in the wrong voting lobby. He locked himself in a toilet so he did not have to vote with the Tories to support staging the EU referendum; something he and his colleagues opposed.

The consequences of that referendum are now, of course, consuming British politics. The SNP is clinging onto the hope that, somehow, the UK as a whole, or at least Scotland, can retain full membership of the European single market.

When I question if the Nationalists will ever realise their dream, Mr Blackford insists this continues to be his party’s “preferred” choice.

“There is no reason why you couldn’t have a deal which recognises our desire to be part of the single market but for the rest of the UK, if that is what is the chosen path, remains outwith that. If you’re going to have a situation between north and south Ireland, where you’re going to have a frictionless border, then there is no earthly reason why that could not work within these islands as well,” he declares.

Of course, the Irish Republic is an independent country; Scotland, as yet, is not.

But then the party leader says something interesting. “There’s a process of negotiation and if there are other avenues we can explore that would achieve the ends that we desire, then, of course, we would be happy to consider them.”

He mentions the Scottish Government’s options paper on Europe, which makes reference to the European Free Trade Association and the Norway and Swiss options, which are seen as partial memberships of the single market albeit with no powers over the rules of the club and with a membership fee to pay.

Stressing once more the SNP’s preferred route to prosperity is through full membership of the single market, Mr Blackford again notes: “If there are other ways we can do that on the basis of compromise, then, of course, we would be prepared to look at those.”

He insists the “key determinant” is to protect the economic interests of Scotland. “What we don’t want to do is to get into the negotiations at the moment because we want to do that with the UK Government and make sure we can protect our interests.”

Which sounds like the desire for full membership of the single market is a hopeful starting point to negotiations rather than a determined conclusion.

The Highland MP was then asked if he agreed with Sir Vince Cable, the next leader of the Liberal Democrats, who has suggested that, given the difficulties, complexities and uncertainties of the Brexit process, Britain’s withdrawal might never happen.

Mr Blackford pauses to ruminate. “You respect the vote that took place throughout the UK in 2016,” he declares.

But he then adds: “If we are talking about a hard Brexit and not just an economic threat to Scotland but to the rest of the UK, is it inconceivable that the country could be in a different position than the one it’s in today? No it’s not. But it’s not for us to make a judgement on that.” Not yet, anyway.