Imagine two paddocks at the edge of a city. They have the same soil and access to the same roads and pipes.

Then town planners allow homes on one side, but not the other. The first can be worth many times more. Nothing physical has changed. The rule has.

Families pay through dearer sections, mortgages and rents.

The new Planning Bill promised ‘competitive urban land markets’. That means having enough sites available that one planning line cannot make buildable land scarce.

When the Bill arrived last December, the promise was there. The means of keeping it were not.

Our February submission explained what was missing. In May, our report Beyond Targets showed how councils can declare they are delivering on their housing targets, on paper, while land and development opportunities remained scarce. Prices reveal what the spreadsheet hides.

The select committee returned the Bill in July. The mechanism was still missing.

In late July, Housing Minister Chris Bishop invited competitive advice. For three weeks, Eric Crampton and I joined a group of urban economists to answer two questions: who would decide whether planning rules were making land scarce and what would happen next?

Last week, Bishop tabled an amendment to add a world-first regime to the Bill: an Urban Land Market Officer.

The Officer will gather evidence, examine prices and planning rules, then publish a finding. If local planning helped cause a shortage, the council must follow a regulated process to address its part, including acting in a timely way. Town planners can no longer mark their own homework.

It is not everything we proposed. The Officer will sit inside the Ministry it may need to criticise. The scheme will not begin automatically, and ministers will shape it through later rules. Councils will choose the remedy with a deadline yet to be determined by the regulated process. There is no independent check on their response.

Parliament rarely sees nights like 25-26 August.

Bishop introduced something novel. No other country has given an independent officer this job. Labour MP and former housing minister Phil Twyford told the House that Labour supports the new system, calling the consensus across the aisle “a real bright spot”. They then debated it like statesmen, Twyford trying to strengthen it.

He wanted it to be more independent from Ministerial interference and firmer duties on town planners to fix council actions that stop the market from working.

Labour’s amendments lost. Yet Labour has now put on record that it wants the Officer strengthened, not scrapped. That makes the scheme more likely to survive a change of government.