Don't know what Cameron was on about when he was talking about 'segregation'. Posh Tories like him love segregation. People like him are segregated from birth, sent off to schools where they only meet other boys like him, a place waiting for them at Oxbridge or Durham or Bristol, a business where someone in the family is employed, or in his case, in the Tory Party, where people like him enact laws which help society become more segregated, none more so than in education where the creation of academies and free schools has encouraged groups of parents and/or teachers to set themselves apart and create a kind of 'only-us' type schools, of many different kinds - our religion, our outlook, single-sex and so on.
Mixing is anathema to people like him. Their phoney notion of freedom is entirely based on people's 'choice' to be in public institutions separated off from whoever 'I' might think of as 'them'. And if 'I' am not given that choice then if 'I' have money, 'I' am told it's 'freedom' to buy that separation and segregation.