Tristram Hunt declined to comment. Those words leapt out in a New Statesman article earlier this year describing how private and state schools could demolish walls between them. Andrew Adonis, Michael Gove, Anthony Seldon, even myself, all wrote articles. Tristram Hunt? He declined to comment.

The shadow education secretary was rightly lampooned for his silence. When private school students make up just 7 per cent of the population, but capture more than 35 per cent of Oxbridge places and the plum share of powerful roles then there is an inequality worth talking about.

In the background, however, Hunt’s team started to work on a policy. Last week he announced it.

The proposal is simple: private schools will have to share their resources with state schools if they wish to continue receiving an 80 per cent tax break on business rates. Current estimates suggest the relief is worth a minimum £147 million per year.

A media storm followed the announcement. Critics from the right focused on two issues: the bureaucracy such a policy would require, and the fact that many private schools already collaborate with state schools. Left-wing detractors called it patronising and decried the idea that state school teachers could learn anything from the private sector.

Wouldn’t we rather teachers taught than wrote lengthy charity submissions?

Hunt has been at pains to say that this is about more than sharing teachers. It is about releasing resources locked up behind private school gates. This might include teachers – but also musical instruments, playing fields, artists-in-residents, debating coaches, leadership experience. It’s not a question of whether these things exist or would benefit from being shared. It is simply whether the schools, of both stripes, are willing to do it.

Private schools do already demonstrate their public benefit in charity accounts submitted each year and available for public perusal. However, in Parliament earlier this week, Hunt said that one school was receiving £180,000 of tax relief “just for showing its pupils’ artwork on the walls”. A quick check of accounts show that it’s a bit of an elaboration to say the benefit was only for doing this.

But it is true that, in 2012, Bedales Prep School collected a minimum tax relief of £180,888 and said that the public benefited from free and open exhibitions of its pupils’ work. Another school secured £66,074 of relief, but its accounts fail to mention any state school partnership.

This does not mean the schools aren’t collaborating with state schools, or that being isolated is common. It might be that they chose not to spend great amounts of time writing detailed reports – after all, wouldn’t we rather teachers taught than wrote lengthy charity submissions? What it does show, though, is that so far the government has not been keeping an eye on and challenging schools about the benefits accruing specifically to state-educated children.

There is a fine line between “bureaucracy” and “transparency”, and when nearly £150 million is on the line, it isn’t unreasonable to ask private schools to spend time properly demonstrating that their benefit to the public equals the one they get from the exchequer.

The plan is also less bureaucratic than expected. Private schools will need to create an annual action plan outlining their school partnerships and submit this to the Independent Schools Inspectorate (ISI) as part of the usual inspection cycle. It is proposed that ISI will decide if the school is meeting required standards, asking for additional information if not. If a school then fails to change, ISI will inform the local authority that the school is no longer eligible for business rate relief.

The paperwork is little different to what is completed by the schools already on top of this brief. That “private schools do all this already” has been a frequent argument against Hunt. But, if it is already being done, why the complaints?

More convincing are those people who say Labour should just scrap the tax relief. Why share theatres with private schools when, at £147 million savings per annum, you could build 100 theatres each year and give them away to state schools?

But this is about more than money. A problem of a “private versus state school” mindset is that the two groups become adversarial. Private school kids fear being beaten up on their way home, and state school kids feel like less-loved siblings compared with students taught in glorious surrounds while their school roof caves in.

The power of Hunt’s proposal is the scope for reuniting this division. Why not have sports teams where private and state pupils play together? Why not joint orchestras, theatre productions, school trips and school councils? It is harder to fear people you know – and children soon come to realise that private school roofs also cave in, and state-educated kids typically flee from fights.

If the partnerships don’t work then, sure, Labour could think about swiping the cash. In the meantime, at least Hunt has taken a step towards bringing down the Berlin Wall. Plus, it is nice to see him finally commenting.