A Labour-SNP “progressive alliance” at Westminster following the 2020 General Election is possible, Alex Salmond, the former First Minister, has suggested.

Speaking on his LBC weekly radio phone-in, the MP for Gordon was asked if in four years’ time the Tories faltered after a Brexit upset and Labour and the Liberal Democrats did better than expected, could the SNP form part of a “rainbow coalition” led by Jeremy Corbyn’s party, he replied: “Anything is possible in politics and, therefore, we should discount no possibility whatsoever.”

Mr Salmond said the Conservative Government did not look sure-footed on Brexit at the moment and that there were plenty of pitfalls ahead and that “some of these chasms might appear early on in the New Year”.

Asked what the SNP demand would be in any cross-party deal, he said it would be the formation of a “progressive alliance”.

It was suggested that Scottish independence would form part of the Nationalists’ wishlist as part of that alliance but the former SNP leader replied: “A progressive alliance does not depend on a concession of independence. It might involve an independence referendum. It would certainly involve the people of Scotland having the right to choose independence.”

He explained how a progressive alliance might involve a range of policies like, for example, proportional representation.

Asked if any pact, agreement or coalition, would have, at least, to involve an independence referendum, Mr Salmond said: “Yes. It would have to involve progress for Scotland on the constitutional question.”

He said that asked to postulate between influencing a government on progressive lines or being subjected to a Tory majority government, he would choose the first.

Noting how the prospect of a Lab-SNP alliance did not work out after the 2015 General Election, Mr Salmond said: “The reason it did not work out the last time was because Ed Miliband could not win any seats in England; he could hardly win any seats at all, he lost lots of seats in England. Therefore, the whole thing didn’t come off.”

He added: “It’s possible this Conservative government might run towards the rocks very quickly on the European issue. It’s happened before and certainly could happen again.”