Theresa May will frustrate Nicola Sturgeon’s hopes of a second independence referendum for as long as six years as she draws the battle lines for her defence of the “precious, precious Union”.

The Prime Minister decided Scotland should not be given a vote until Scots have seen how Brexit works out, and will call Nicola Sturgeon’s bluff by challenging her to prove at the next Scottish elections in 2021 her claim that she has a “cast iron” mandate for a new poll.

Mrs May infuriated the First Minister by formally rejecting her demand for a referendum between autumn 2018 and spring 2019, saying “now is not the time” for a vote on the future of the Union.

Ms Sturgeon described the decision as a “democratic outrage” and said she remained "determined" to hold a poll on her own timescale. She added that she would "consider my options and what I should do" if a Scottish Parliament request for permission to hold a referendum is turned down.