Boris Johnson is not a good role model for children, according to a top government adviser who is known as Britain’s strictest headmistress.

Katharine Birbalsingh, chair of the social mobility commission, told Sky News’s Beth Rigby Interviews that from his personal life to his messy hairstyle, the three-times married prime minister causes her to “raise an eyebrow”.

She added that while she did not know all the details of the partygate scandal it did make her pause and think “I certainly would never be able to put him up and say, be like him”.

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Ms Birbalsingh rose to prominence when, as an inner London teacher, she addressed the Conservative party conference in 2010 to say the education system was broken and that it kept “poor children poor” – upsetting some in the teaching profession but winning a standing ovation from Tories.

She went on to co-found Michaela Community School in Wembley, north London, where she is now headmistress – and has strict rules on uniform and behaviour.

Ms Birbalsingh told Sky’s political editor Beth Rigby that she is a “small c conservative” but not a member of the Conservative party.

Asked if she felt the PM is a good role model for children, she said: “No, I do not think so. I don’t. I wish he could be, but he isn’t. And that is a bit sad.

“I like Boris, I don’t think he’s a bad guy… But I do not think he’s a good role model for children.”

Asked why, she said: “Well, his personal life for instance. That does make me sort of raise an eyebrow.

“His hair – you know, we’ve got strict rules at school.

“I looked at his hair and I thought, gosh, I couldn’t put him up on the wall and say, let’s all have haircuts like him.

“You might think, that’s a bit pedantic and that’s a bit silly, but it isn’t actually I think for our children.

“It’s important to look professional, and sometimes Boris looks professional, but sometimes he’s not professional enough for me, put it that way.”

Asked about “family values”, Ms Birbalsingh said: “It’s a sort of thing that makes me pause a little bit… I’d say I’m relatively liberal about these things to a certain extent but he does kind of push the boat out a bit on that.”

She said she did not know “the ins and outs enough about all the recent partygate stuff”.

“I’m too busy working to follow all of that, but it does sort of make you pause and go hmm, I certainly would never be able to put him up and say, be like him. I couldn’t do that.”

Ms Birbalsingh’s comments come a day after another government adviser was forced out of her role following remarks about the PM.

On Tuesday, Baroness Morrissey – a prominent City figure who had been serving as lead non-executive director at the Foreign Office – branded Mr Johnson a “liability” and said he should resign during an LBC interview.

Foreign secretary Liz Truss was understood to have been outraged by the comments and ordered her to be sacked.