There is an often overlooked problem at the heart of Angela Rayner's bid to build 1.5m homes over the next five years: economics.
Even if the Housing Secretary's planning reforms succeed in pushing councils to find more land for development and in dramatically ramping up planning consents, she will run into a new hurdle: companies do not want to build them.
Despite Britain's huge housing need, the blunt truth is that it will not make financial sense for developers to build 1.5m new homes.
"This is the biggest constraint," says Iain Jenkinson, of CBRE, an investment company.
Across the UK's entire construction sector, 70pc of the projects that receive planning permission actually get delivered, says Jenkinson. When it comes to building homes, that share drops to 50pc.
These properties are never constructed because the sums do not add up. The cost of building them is too high compared to the price the developer will receive upon selling, says Jenkinson. This calculation is influenced by everything from interest rates to building material costs and the supply of homes on the market.
Although lots of people need homes, only a small proportion can afford to buy them. In turn, this means there is a ceiling on how many homes developers will build. Ultimately, there is a cap on the number of homes housebuilders can sell at the prices they want.
Beyond private enterprise, England's councils are grappling with a widespread financial crisis and have no capacity to ramp up building at scale again. Housing associations are grappling with building safety remediation costs in the wake of the Grenfell fire.
To deliver on Labour's manifesto pledge to "get Britain building", Rayner must break with tradition and admit that the UK's dream of mass homeownership is broken. If Labour wants to deliver 1.5m new homes, ministers must accept that many of them will be for renters rather than owners.
That is because there is one group that is keen to build: pension funds. But these institutions want rentals, not properties for sales.
Pension funds are drawn to rental properties because it gives them a steady stream of income and an asset. They want stable, long-term returns that will beat inflation for their savers. Building and selling homes does not deliver this but building homes and letting them out does.
"I think institutional capital could potentially fund half of what's needed," says Bill Hughes, of Legal & General, which manages £1.2 trillion in assets.
"The Government has talked about 1.5m homes. I think there is no reason why by the end of that five-year period the majority of housing couldn't be produced by the private [institutional] sector."