Whitehall and private firms have been too focused on using targets and quotas to boost the fortunes of people from poorer backgrounds rather than promoting “equality of opportunity”, according to Liz Truss.

Ms Truss, the Foreign Secretary and equalities minister has tasked a Conservative headteacher with tackling “the soft bigotry of low expectations” in Britain.

On Saturday night, she told The Telegraph she had chosen Katharine Birbalsingh, who has been described as the country’s toughest head teacher, as the Government’s new social mobility tsar.

Ms Birbalsingh, 48, who leads the Michaela Community School in north London, has been asked to focus on “education, enterprise and employment” when she takes over the running of the Social Mobility Commission, charged with helping to “level up opportunity across Britain”.

Ms Truss wants to “refocus the Government’s social mobility work” on narrowing gaps in “education, employment and enterprise” between the South East and rest of the country.

She said of Ms Birbalsingh: “By expecting high standards and not indulging the soft bigotry of low expectations she produced amazing results at Michaela school and gave those children the best chance in life. She will bring that same attitude to the commission and be a loud champion of equality of opportunity.”

A source close to Ms Truss said she believed there was too much of a focus in Britain on “targets and quotas” which “artificially fix an outcome” rather than “promoting equality of opportunity and addressing the root causes of inequality”.

George W. Bush used the phrase “the soft bigotry of low expectations” to describe how disadvantaged children became “trapped in failure”.

Ms Birbalsingh’s appointment is likely to be controversial. In 2010, as the then deputy head of an inner city school, received a standing ovation at the Conservatives’ annual conference when she described the state school system as “broken because it keeps poor children poor”.