A tax avoidance racket by privateers leeching millions from the Tories' backdoor privatisation of education in England is laid bare today in a damning new Trades Union Congress exposé.

A stunning £77 million in public money has been snatched away from schoolchildren and stuffed into the pockets of consultants since the Tory-led coalition took power in 2010.

Accountancy firm PKF - whose parent company BDO offers "offshore tax planning" to "high net-worth individuals" - has been handed £8 million.

Headhunters Veredus, which is part-owned by outsourcing giant Capita, gobbled up £4.7m.

And lawyers, accountants, estate agents and management consultants are among the 12 other profiteers to have cashed in, according to Department for Education figures.

TUC general secretary Frances O'Grady said it was proof that Education Secretary Michael Gove's reforms are driven by "free-market dogma."

"Money that should be spent on children's education is instead being swallowed up by private firms and in expensive property deals," she said.

"Companies have been allowed to cream off millions in profits from running schools and support services.

"Let us be under no doubt - our world-class public education system is under threat from corporate interests and our schools, colleges and universities are now less accountable to taxpayers and local communities."

Millions more have been siphoned off by school directors and trustees who charge for their services through companies that they own.

The number of privateers applying to run schools has tripled since 2011.

The study also reveals how three of England's biggest academy chains - Ark, Harris Federation and the David Ross Foundation - are led by Tory peer Lord Fink and donors Lord Harris and David Ross respectively.

And over £500m has been splurged on building new free schools for a tiny fraction of pupils while England is gripped by a school places crisis.

Shadow schools minister Kevin Brennan said: "At a time when there is a school places crisis in some parts of the country funds should be prioritised to meet those needs, rather than spent on the bureaucracy of setting up free schools in areas where there are already surplus places."

NUT general secretary Christine Blower demanded that "every last penny" of taxpayers' cash "be used to improve our children's education not lining the pockets of a few."

She warned that schools have started answering to shareholders instead of parents, pupils and communities.

Restoring democratic accountability is central to the TUC Education

Not For Sale campaign to be launched on Tuesday.

It will see teachers from primary schools to universities unite with students and their parents to weed out profiteers' roots before they take grip.

Legislation to ban profits being squeezed from schools, ensure that only qualified teachers lead classes and a public register of interest for every school are other key demands.

Education union ATL leader Dr Mary Bousted said: "Simply banning sponsorship of schools would end the conflicts of interest, the cronyism and distorting a school's aims to making a profit."

Unions will also campaign for an end to massive public subsidies being given to profit-making colleges and universities without any quality checks.

Academics' union UCU leader Sally Hunt said that the government's actions have created an uncapped, unregulated shadow higher education market.

"Our schools, colleges and universities are being told to manage with less money while private companies make a fast buck out of our public education system," she said.