Or, if you marry someone in the 'Toby Y income' (i.e. 90% of the population, married or not...), and your children are very bright, move to a super selective grammar school area where the children there will give the most academic children at the most academic private schools, a good run for their money in the competition for Oxbridge/Russell Group universities. Every single pupil in my DCs' GS 6th form has a place at either a RG university or Oxbridge (Oxford being the university admitting the most pupils).
Money doesn't necessarily = cleverness, I am afraid, but it does buy better results from not very bright/average children in the first place, which is Not Very Fair, but then most people aren't interested in fairness, are they???
Toby Young et al will have to see how all the private schools with the Nice but Dim mixed ability intake manage to get their results and copy them for his school to succeed.
But education isn't JUST about the bright children, it's about the OTHERS too.
(Disclaimer: only ranting about GSs to make a point that it's not only those who pay who are miraculously Very Clever to start with )