Ian Blackford is the Scottish Nationalist MP for a vast tract of north-west Scotland, and the leader of the SNP’s 48-strong band of Westminster MPs. He is a prominent champion of the cause of Scottish independence, a cause which represents one of the biggest challenges facing prime minister Boris Johnson over the next five years. Back in 2014, Scotland voted by 55% to 45% to remain in the UK. At the time, it was billed as a ‘once in a lifetime’ decision. But since then, Britain has left the EU – against the wishes of a clear majority in Scotland – and the SNP now argues that this material change in circumstances gives Scots the right to another vote on independence. The SNP's grip on power in Scotland is currently unassailable, so a protracted political stand off between Edinburgh and London seems inevitable. The nationalists have plenty of passion, but do they have a winning strategy?