Boris Johnson has faced fresh questions over his honesty and transparency as he refused to say how many children he had fathered and looked set to duck a TV interrogation.

The Prime Minister also angered some of his natural supporters on the right by suggesting there would be more state intervention in the economy after Brexit.

The criticisms came as the Tories published a “Brexit roadmap” setting out how the UK Government would operate outside EU state aid rules.

It said there would be a new state aid regime making it “faster and easier” for the Government to intervene to protect jobs in troubled industries, and a “buy British” approach to procurement.

Mr Johnson said his aim was not to bail out failing business but to ensure a “level playing field” after Brexit.

However, the business lobby group theInstitute of Directors said the proposals suggested a “retreat away from free and open markets” which would have “clear implications” for the UK’s ability to negotiate a post-Brexit trade deal with the EU.

Allie Renison, Head of Europe and Trade Policy at the Institute said: “It seems like a bad solution in search of the wrong problem.

Propping up failing enterprises and obliging public bodies to ‘buy British’ could end up unfairly protecting and subsidising large incumbents at the expense of true competition and new entrants to the market.” 

The free market think-tank, the Institute of Economic Affairs, also warned the greater use of state aid to help firms in trouble would “translate to veiled support for cronyism”.

Labour said the Tories had powers to support UK industry but failed to do so.
Shadow transport secretary Andy McDonald said the Tories “sat on their hands and used state aid as an excuse” when refusing to intervene to save a steel works in his Teesside seat in 2015.

Mr Johnson appeared at his party’s event alongside former Labour MP Gisela Stuart, a key member of Vote Leave, who urged a  Tory vote. 

She said: “In this election, I will not vote for Jeremy Corbyn but I can vote for Brexit. A vote for Boris Johnson this time around is a vote to get Brexit done. 

“But let me be clear, voting for Brexit this time does not make me a Tory now or in the future.”

In another embarrassment for Labour, it emerged the party had told 20 of its call centre staff in Newcastle that their contracts would end after Christmas. 

Mr Johnson faced an uncomfortable moment on an LBC phone-in when a caller raised a 1995 article in which he blamed single mothers for “producing 
a generation of ill-raised, ignorant, aggressive and illegitimate children”.

The caller, Ruth from Oldham, said she was a single mother and asked: “Why are you happy to criticise people like me, when you refuse to discuss your family?”

Mr Johnson, who has four children by his former marriage and at least one outside it, said the quotations had been taken out of context and dated from before his political career.

Host Nick Ferrari asked him how many children he had and if he was “fully and wholly involved in their lives”.

Mr Johnson said: “I love my children very much but they are not standing at this election and I’m not therefore going to comment. I am not going to put them on to the pitch in this election campaign.”

After refusing to take part in a Channel 4 debate on climate change on Thursday, Mr Johnson was also at the centre of a row with the BBC over a possible interview with Andrew Neil.

Nicola Sturgeon and Mr Corbyn submitted to gruelling half-hour interviews with the veteran journalist last week, and Jo Swinson and Nigel Farage are due to face him next week. But Mr Johnson has so far refused to confirm when, or if, he will do likewise.

It emerged the BBC has now refused to allow him to appear on this weekend’s flagship Andrew Marr unless he agreed to an encounter with Mr Neil.

A BBC source said Mr Johnson “won’t be doing Marr until we have confirmed and announced a date for the Neil interview”.

Shadow chancellor John McDonnell said the BBC should be angry at being “played” by the PM, who he said was running down the clock to duck scrutiny before December 12.

He said: “He is doing this is because he thinks, like his Bullingdon friends, that they are above the rest of us, that they don’t need to be held to account, they don’t need to be treated like the rest of us.”

On a visit to Scotland, Chancellor Sajid Javid accused Nicola Sturgeon of “getting into bed” with a party “riddled” with anti-Semitism in order to secure an independence referendum. 

Rejecting the SNP’s call to devolve immigration, he nevertheless suggested the salary threshold for a work visa could be different in Scotland after Brexit.

Mr Javid ordered a review into the proposed £30,000 threshold for immigrants in June, after complaints from employers that it would exclude essential staff on lower wages.

Campaigning in Stirling, the most marginal Tory-held seat in Scotland, the Chancellor said: “I think that having a system where the UK sets the rules around control is the right way forward.  

“In Scotland, if you take the farming community, the fishing community, we need to make sure that they have the workers that they need and many of those do come from abroad.

“We will always be listening to Scotland’s needs as well as the needs of the rest of the UK when it comes to setting any kind of salary threshold. I think there is a case for Scotland to have its own approach to make sure it is working for Scotland.

“But if you look at the trading that takes place between Scotland and the rest of the UK it is hugely important that there are no artificial barriers created and that’s what a devolved immigration system would do. It is in no one’s interest.”

The Chancellor also criticised the First Minister for her willingness to work with Jeremy Corbyn in the event of a hung parliament in order to secure Indyref2, despite concerns about the Labour leader in Britain’s Jewish community.

He said: “If Corbyn can’t get a majority then he will absolutely have an alliance with Nicola Sturgeon. It’s clear they have already agreed that they would have another divisive referendum on Brexit - but also a divisive referendum on independence. That will be chaotic – two referendums in the UK in 2020. Nicola Sturgeon will have to accept that, yes, she might get her beloved referendum with a Corbyn-Sturgeon alliance, but she will be getting into bed with an individual that has serious issues with Britain’s Jewish community... and has a problem of anti-Semitism riddled throughout his party.”

The Conservative Party has faced criticism over Islamophobia, with the Muslim Council of Britain accusing it of approaching the issue “with denial, dismissal and deceit”.

Mr Javid said the SNP has been “absolutely obsessed by independence referendums and as a result they’ve neglected delivering on everyday services for the Scottish people”.

SNP candidate Stuart McDonald said: “Even the Tories now admit that their one-size-fits-all approach doesn’t work for Scotland. The Tory approach to immigration – ripping us out of the EU and imposing a ‘hostile environment’ 
– poses enormous risks to our economy and our public services.

“Ultimately, Scotland should make these decisions for ourselves - putting our values and economic interest at heart of our immigration system. We need to escape Brexit and put Scotland’s future in Scotland’s hands - not Boris Johnson’s.”

On anti-Semitism, the SNP added: “There is no place for anti-semitism in society or politics. Labour have been guilty of an abdication of leadership on the issue and must do much more to win the trust of the Jewish community.”

Ms Sturgeon will today brand the PM “the biggest ever threat to the NHS”.

In an election address in St Andrews, the First Minister will say he is “a real and present danger to our precious, publicly run health service”.

She will tell activists in North East Fife, where the SNP’s Stephen Gethins is defending a majority of just two votes, the PM’s Brexit plan would make it harder to recruit health service staff from Europe and depress the UK economy, straining NHS budgets. 

She is expected to say: “Compared with EU membership his deal could cut Scotland’s national income by £9 billion by the end of the next decade.

“And if Boris Johnson takes Scotland and the UK out of the EU with no trade deal at all next year – which is looking increasingly likely – the cost could be £12.7 billion.

“That’s the equivalent of around £2,300 per person in Scotland.  

“US drugs firms want “full market access” to the NHS in any Tory-Trump trade deal – raising the prices the health service has to pay.

“The Foreign Secretary has even complained that Scotland has too many nurses and ambulance staff compared with the rest of the UK.

“This all adds up to a sustained Tory assault on Scotland’s health service.

“The NHS will never be safe in Boris Johnson’s hands. 

“In Scotland the SNP is the challenger to the Tories in all 13 seats they hold.

“So in Scotland only a vote for the SNP can lock the Tories out of office and protect our NHS from Boris Johnson.” 

Scottish Tory leader Jackson Carlaw will focus on the Union bringing the massive UN Climate Change Conference COP26 and its 30,000 delegates to Glasgow next year. 

At a tree-planting ceremony in Newton Mearns, he will say the event demonstrates how the UK intends to remain an “open and active player in the fight to protect our planet”.He said: “As we celebrate St Andrew’s Day today, it’s apt to look forward to what promises to be a great year ahead for Scotland.

“Most of all, we are looking forward to bringing the world to Glasgow, as it prepares to host COP26, the biggest summit the UK has ever staged. As many as 30,000 delegates will come to the city for what is likely to be a vital staging post in global efforts to deal with climate change.”

“2020 can be our chance to show worldwide leadership on the vital issue of climate change, and to show that the UK remains an open and active player in the fight to protect our planet.”