Anthony Seldon, head of Brighton college, and Tony Blair's unofficial biographer, unsuccessfully attempted to move from a private to a state school as a classroom teacher early in his career.
Since then he has applied for deputy head and headteacher posts at two unnamed state schools, but was turned down each time.
Dr Seldon, who will take over at the pound;21,900-a-year Wellington boarding school, Berkshire, in January, also attempted to set up a job exchange between Brighton college and a state school, but the idea was shelved. "I was told the level of bureaucracy would prohibit it," he said.
Last year Tristram Jones-Parry, the retiring head of the private Westminster school, was refused a state school job because he did not have qualified teacher status.
Dr Seldon, 52, has QTS and also holds an outstanding teacher award from King's college, London. He once asked at an interview for a state-school job whether he was at a disadvantage coming from the private sector. "I was told 'no comment'. There were obviously better candidates but I would not underestimate the degree of difficulty one has transferring between the two sectors.
"The apartheid that exists between the state and independent sector is deeply unhelpful. The Government has done good work but it should have done much more."