Last week, shadow education secretary Tristram Hunt announced Labour’s plans to strip independent schools of their current tax breaks if they do not sufficiently support state schools. Writing exclusively in the Ham&High today, Mr Hunt praises local independent schools and hits back at criticism from his old Hampstead school.

London’s northern foothills have long proved fertile ground for progressive politics. Hugh Gaitskell, Antony Crosland, Michael Foot - numerous scions of the Labour movement have called this area home.

Even Karl Marx could not resist the allure of Hampstead Heath, spending Saturday afternoons there performing Shakespeare recitals with his adoring daughters.

This spirit of social responsibility is reflected in the contribution of the area’s private schools towards the local state sector. University College School - which I attended - sponsors an academy in Westminster, King Alfred provides curriculum resources to a special school in Barnet, whilst so extensive are Highgate School’s partnership activities that it is no understatement to call it a national leader.

However, we should not make the mistake of assuming such public-spirited sensibilities are the norm. They are not.

As Ofsted Chief Inspector Sir Michael Wilshaw has pointed out just three per cent of private schools sponsor an academy, whilst only a further five per cent share teaching resources.

Some private schools list opening up their gardens, displaying artwork and complying with employment legislation as a “public benefit”.

Labour’s new Schools Partnership Standard would set out tough and transparent criteria which puts an end to this charade.

And if rigorous inspection proves some private schools are doing nothing beyond their walls, then yes we would remove the state-subsidy that comes via their £140m a year business rates relief.

UCS headmaster Mark Beard might call that “offensive bigotry”. I would call it a simple request that all private schools meet their social obligations.

This policy is not about attitudes towards private education. Neither is it about suggesting private schools have all the answers. It is about the Labour Party’s ambition for a truly national education system which helps break down the barriers stifling social mobility.

All private schools collaborating like Highgate School would represent a significant step down that road.