To the OP, many of the schools in London are dominated by working class kids (and those who are middle class have equivalent spending power as anyone's who's working class outside the city). All are majority ethnic minority, and many cover the most deprived and underfunded districts /boroughs in the country.
However, there is a phenomenon called the 'London Effect', that these kids outperform the rest of the country -even the lowest scoring in the capital are some of the highest outside it. A lot has been said about the high value of education that the African, East European and Asian families instill on their kids, another on the study culture among so many peers (even unruly kids will get their revision done when it comes to it), but no one's really sure. I imagine also that city kids get very progressive and often inspiring teachers, and have far more cultural access from living in a multitudinous city. They also get sea change and dynamism, if there are any changes and experiments that can be rolled out in education by forward thinking Head Teachers, it will likely be in city academies. These are the kinds of people that recognise that rappers are poets (with as much obsession on flow, rhyme and performance as the Victorians), suffering finds an outlet/ salve in creativity, and that gangs can not just be replacement families, but powered by masterminds that they get to personally know. Many of the teachers are there to inspire and change, not for the money, especially when they're consciously picking these schools rather than smaller provincial ones, with far less hassle.
https://sqte.at/en/beispiel-london-e...hese%20schools.
For example Brampton Manor School, in the country's most deprived borough (with the most immigrants) annually sends off more Oxbridge entrants (the country's two best universities, Cambridge or Oxford) than Eton College, a few hundred metres from the Queen's castle where she would often attend their ceremonies. Brampton received 89 offers this year -that's a poor State school overtaking the world's most elite one ($55K a year fees but with far worse entrance exams, where traditionally royal families from round the world send their kids), and where the nation's Prime Ministers usually get hired from.
Eton College is also very multicultural, and 25% of the boys receive financial assistance or on scholarship, but it goes to show league tables, class or funding aren't all that. Only recently they ditched the top hat the boys used to have to wear.
https://timpestridge.co.uk//images/P...-Eton-9681.jpg
Eton College complex:
I work on a schools programme in the busiest attraction in the country - we get over a thousand school kids visiting each day, and the London schools can often be rowdy and high spirited (well, many of the provincial ones too), especially aged 13-14, who'll think it fine to play football in a shop or food fights at lunch. However before and after, they're much better behaved. Also there's something to be said about what type of
naughtiness the kids get into - there's the kind that get into trouble by being too loud and rowdy as they go round seeing the exhibits, there's the other where the rich kids break into elite groups, find a hiding spot in the Museum and spend the entire time texting and chatting. A favourite spot being the bed display, bless.