A think tank report says a refusal to authorise a second independence vote if nationalists do well at the next elections could undermine the union

Blocking a Scottish independence referendum will be unsustainable if a majority of Scots want to rerun the vote, according to a think tank.

The Institute for Government (IFG), an independent think tank based in London, suggests that the legitimacy of the Union could be undermined if a request to hold another vote is repeatedly rejected.

Its report focuses on the impact of a no-deal Brexit and the Union. Under a section called “Mitigating the risks to the Union” the IFG wrote: “The Scottish Government intends to hold a second independence referendum. This will need the agreement of Westminster.

“However, if there is a clear majority in Scotland for a second vote on independence, it would be unsustainable and counterproductive for the UK government to block