RUTH Davidson has re-ignited her Brexit bust-up with Boris Johnson by taking pot-shots at the Foreign Secretary on the eve of the UK Conservative conference.

The Scottish Tory leader, who previously accused Johnson of lacking a plan for life outside the EU, warned she would “make sure he applies himself to the task of Brexit”, suggesting she still does not trust the unpredictable former London Mayor do it unsupervised.

Asked if she took Johnson seriously, Davidson said pointedly: “I take the office of Foreign secretary seriously and I always have.”

Pressed on whether she took the man seriously, she said she had been “pleasantly surprised and impressed” when she met him a fortnight ago, again suggesting a low opinion of Johnson.

Davidson famously clashed with 'BoJo' in the final TV debate of the EU referendum, telling him his glib position on Brexit job losses was “not good enough”.

Her latest remarks, made in a press briefing ahead of a high-profile appearance at the Tory conference in Birmingham this week, are a reminder of Tory divisions over Europe.

They could also prove embarrassing for Theresa May, who chose Johnson to be Foreign Secretary, as Davidson is the warm-up for the Prime Minister’s final speech on Wednesday.

Despite May repeating her opposition to a second independence referendum on Friday, Davidson also stuck to her belief that it would be an error for Westminster to block one.

She said: “I don’t believe that the UK government should go round threatening to block a second referendum, in the same way that I thought it was wrong for the Spanish government to say that they were going to block a Catalan referendum.

“You saw what happened there, and the way people got onto the streets of Barcelona. I think it would play directly into the Nationalists’ hands.”

But Davidson added it was “nonsense” for Nicola Sturgeon to interpret Scotland’s vote to Remain as a “proxy” for Indyref2.

“I’m as strongly pro-Union as I was before. I certainly don’t think that any questions that Brexit throws up are answered by ripping Scotland out of another union that’s worth four times more in trade and is with our nearest neighbours and closest friends.”

The SNP has criticised Davidson for appearing to flip-flop over Brexit recently, going from a passionate Remain campaigner to advocating making EU withdrawal work.

The Edinburgh Central MSP said she wasn’t going to sulk when there was hard work ahead.

“I’m determined I’m going to pull my weight and do as much of it as I can, rather than sit in the corner and moan that I didn’t get the result that I wanted.”

In a speech at a conference fringe today, Davidson will call for the SNP’s universal Named Person scheme to be scrapped, and say she would put the £10m a year saving into a new Crisis Family Fund to help families in greatest need instead.

She will say families are the “best incubator of social justice” in society, and the state should support them, not snoop on the children on the grounds of monitoring their well-being.

“A single point of contact – fine. Let’s make it easier for parents and children to access services they need. But a state-appointed guardian with powers to go behind parents’ backs? No.”

An SNP spokesman said: “It speaks volumes about the competence of Theresa May's Brexiteer Ministers that Ruth Davidson struggles to offer even qualified support for the Foreign Secretary. Just a few months ago Ruth Davidson was happy to tear into Boris Johnson over the EU – the question is why she now acts like a born-again Brexiteer if she thinks our EU membership is so important."

LibDem MSP Mike Rumbles said: “Boris is a man who was willing to mislead the people of Scotland over the consequences of a Brexit vote because he thought it might further his career. Ruth Davidson is right not to rate him but the hard fact is that he is the Foreign Secretary that her party has inflicted on us all.”