Young black people are being held back from success in school by teachers who “are scared of being called racist” if they discipline them, the woman dubbed “Britain’s strictest headmistress” has claimed.

In a speech at a fringe event at the Conservative Party conference, Katharine Birbalsingh said schools can behave “very differently” towards black children.

“Give that black boy a detention and senior management might start asking you why you don’t hand out the same number of detentions to the white kids,” she said, adding: “It’s hard to explain to the bosses that every disparity between the races is not necessarily explained by racism.

“So it isn’t that racism is keeping those kids back. It’s the fear of being accused of being racist that keeps those kids back.”

Birbalsingh – who famously spoke at the Tory Party conference in 2010 when Michael Gove was education secretary – went on to compare the situation to a council in New Jersey which was accused of racism because black drivers were being stopped for speeding 25% of the time, despite making up just 12% of the population.

“So rather than just assume that the traffic cops were racist, they studied the people who were speeding,” she continued. “Turns out, blacks were speeding more often than whites – 25% more often. Disparity doesn’t always mean racism.”

Birbalsingh, who is headteacher at Michaela Community School in north west London, started off her Sunday evening speech on class and race by suggesting that the media and the “metropolitan elite” focus too much on race when considering life obstacles.

“Any disparity out there between the races and we make a judgement,” she said. “Not that many blacks at Oxford? Racism. Disproportionate number of blacks in prison? Racism. Schooling, culture, the glorification of rap or drill music – we ignore it all because racism makes for a great explanation.”

Birbalsingh continued: “Studies show that between brothers and sisters, the first born will outdo the second child and the second child will outdo the third and so on.

“But for some reason, we don’t talk about first-born privilege and we certainly don’t accuse parents of being bad parents for treating their offspring unequally. We just accept it as one of those things.”

She went to argue that judges who send male offenders to prison are not slammed as “man-haters”, despite the fact more men are sent to prison than women.

“We simply embrace Occam’s razor and assume that more than women are committing more crimes,” Birbalsingh added.

“Yet when the disparity is a racial one, our presumption is the other way round. We assume that race is the deciding factor when it could be a number of things, and class could be tied up with it.”

The Oxford University graduate insisted education is the “number one way to enable social mobility”, with schools being the “crucial deciding factor” of whether a child succeeds or not.

“So does class matter more than race?” she concluded.  “I’ll say no, and that’s because there’s so much complexity to the obstacles holding everyone back.

“But the best thing you can do in life is ignore those obstacles and plough on ahead as if they don’t exist.”

But Birbalsingh insisted that by lowering university entry grades for pupils from deprived schools or backgrounds, “the sense of determination and hunger and focus that is required to succeed in life disappears”. 

Accepting that schools need to “sort themselves out”, she added: “When you just hand out goodies like that, everyone then just puts their hand out.”