Sturgeon faces tough hurdles on road to Scottish independence vote

Analysis: First minister is seeking supreme court ruling but experts say there is nothing new' in her request

There have always been three routes to a second referendum on Scottish independence and, despite the buildup and rhetoric around Tuesday's statement, they remain unchanged - a section 30 order from the UK government; risking a domestic boycott and international opprobrium with a wildcat vote; or putting a referendum bill to the Holyrood parliament and facing down an almost inevitable court challenge.

Nicola Sturgeon told MSPs this afternoon that she had written to Boris Johnson again, the latest of repeated requests for a section 30 order under the 1998 Scotland Act that would grant Holyrood the competence to legislate for another referendum - the previous one happened in 2014 and is a process described as the gold standard" by the first minister.