Wealthy parents "cheat the system" to win places for their children at the best schools, according to a new report.
Parents are willing to employ a raft of cunning schemes including moving house, employing tutors, or sending children to extracurricular activities such as music or drama to gain the upper hand in the school selection process.
The Sutton Trust report, entitled "Parent Power? Using money and information to boost children's chances of educational success", showed that almost a third (32%) of professional parents have moved to an area with better schools, while 18% have moved to live in the catchment area of a specific school.
More than two-thirds (68%) of professional parents paid for extra activities such as weekly music, drama or sporting lessons, compared with one third (31%) of the lowest income parents.
The report highlighted some dubious tactics employed by parents, which included citing a relative's address or buying a second home within the catchment zone of a school.
One in 10 (10%) of upper middle class parents admitted they had attended church services purely so their child could go to a local church state school.
Sir Peter Lampl, chairman of the Sutton Trust and of the Education Endowment Foundation, said research demonstrates that parents with money have a "significant advantage" in school choices for their children.
He said: "This research suggests that those with money actively choose to live near good schools, employ tutors and ensure their children have extra lessons and enrichment activities that are often too expensive for other families to afford.
"This provides a significant advantage in school choice and in developing the cultural capital that is so important to social mobility and later success."
Sir Peter said that school admissions need to be fairer so that the best schools "aren't just for those who can afford to live nearby".
He recommended the use of ballots to ensure fairer admissions and vouchers for working class parents to spend on extra tuition, books and cultural activities for their children.
The trust also called on schools to publish socio-economic data on applications and admission.
Professor Becky Francis, one of the authors of the report, said: "Our research shows just how far equality of opportunity is being undermined by the greater purchasing power of some parents.
"The ability for some parents but not others to use financial resources to secure their children's achievement poses real impediments for social mobility, which need to be recognised and addressed as detrimental to society."
The research, conducted by Professor Becky Francis, King's College London, and Professor Merryn Hutchings, London Metropolitan University, is based on YouGov interviews with 1,173 parents of school-age children.
The Sutton Trust was set up in 1997 to improve social mobility through education.
The report comes just days after Ofsted chief inspector Sir Michael Wilshaw said grammar schools were "stuffed full" of middle class children and do nothing to improve social mobility.
Sir Michael told the Observer: "Grammar schools are stuffed full of middle-class kids. A tiny percentage are on free school meals: 3%. That is a nonsense.
"Anyone who thinks grammar schools are going to increase social mobility needs to look at those figures. I don't think they work."
He added: "The grammar schools might do well with 10% of the school population, but everyone else does really badly. What we have to do is make sure all schools do well in the areas in which they are located."