RUTH Davidson will march her Tories out of Holyrood’s debating chamber if Nicola Sturgeon tries to force a second referendum through parliament without the permission of Westminster.

According to reports in yesterday’s Sun, the Tory MSPs would storm out to do “constituency work” instead.

The Tory threat came as reports suggested the SNP leader would use a “grey area” in the Scotland act to hold a legally valid referendum.

A source said: “We would boycott any attempt to create constitutional conflict by ramming through a Bill outside the legislative competence of the Scottish Parliament. People would see through this as a cynical ruse to stoke up grievance.

“Scots are increasingly sick and tired of Nicola Sturgeon’s antics.

Sturgeon has promised she will spell out her “next steps” after the Easter recess.

An SNP spokesman said: “If the Tory intention is to try to block indefinitely a referendum, that would be utterly undemocratic.

“It will only be a matter of time before the Tories realise that their attempts to diminish and ignore the Scottish Parliament will backfire on them badly.

“The First Minister will set out her next steps in the coming weeks.”

After MSPs backed a motion on a second independence referendum at the end of last month, the SNP leader wrote to Theresa May requesting a Section 30 order to give Holyrood the legal competence to organise the vote.

May is expected to formally tell the Scottish Government that “now is not the time” for an independence referendum this week.

The Prime Minister has been clear that she does not want to get into any discussion about Scottish independence until Brexit means Brexit.

Reports suggest SNP strategists may try and introduce a referendum bill without the section 30 order.

In a question and answer session with students at Stanford University in California during her recent trip to the United States, the First Minister was asked about the process for holding a referendum. Explaining that the Scotland Act had reserved a number of responsibilities to Westminster, Sturgeon said: “One of the things it reserved to the UK government is the constitution, which is quite a vague term. It’s never been tested in court but in 2014 we accepted that for there to be a referendum in Scotland, for the Scottish Parliament to legislate for a referendum, it required the legal consent of the UK government.”

The First Minister later clarified saying, the Scottish Government had no intention of taking the Whitehall to court. If the Scottish Parliament does approve legislation then it is possible and likely that UK ministers would take the Scottish Government to the Supreme Court to strike down the legislation.

Under Section 33 of the Scotland Act, once legislation is approved by MSPs, there is a four-week period before it receives Royal Assent where the UK’s law officers can refer all or part of the bill to the Supreme Court to have it struck down.

Speaking to the Scotsman, Tobias Lock, a senior lecturer in EU law at the University of Edinburgh, said the SNP “could call an independence referendum if they can get it through the Scottish Parliament and it’s not thrown out by the Presiding Officer”.

Though legally competent or not, that would lead to the Tories walking out.

That wouldn’t be the first time MSPs have taken direct action while in the chamber.

In 2005 four MSPs for the Scottish Socialist Party staged a sit-in, and brought proceedings to a halt for almost an hour.

National columnist Carolyn Leckie, and her then colleagues Rosie Kane, Frances Curran and Colin Fox were protesting Jack McConnell’s refusal to intervene and allow a protest march outside the Gleneagles Hotel at the G8 summit that saw the world’s leaders come to Scotland.

The SSP protest angered others MSPs, and saw the four suspended from the parliament for a month, with all their wages and allowances stopped.

Then Tory leader David McLetchie described the SSP’s antics as “infantile, undemocratic and an abuse of their privileged status as MSPs”.