In the upcoming spending review next month, Labour is expected to unveil a significant social housebuilding program, as suggested by Angela Rayner, who also hinted that the party will have betrayed its "moral mission" if it does not.

The deputy prime minister stated at a Labour Conference event on Sunday that she anticipated a social housing commitment from Rachel Reeves, the chancellor, next month, given the pressure on the government to construct hundreds of thousands more social housing units.

Over the length of the current parliament, Labour has committed to building 1.5 million new homes; however, experts argue that this would not be feasible unless funding is secured to construct at least 90,000 socially rented homes and apartments in England annually.

Asked about that target at a panel event organised by the homelessness charity Shelter, Rayner said: “Unless we address the social and council housing problem in this country, then we’re really not going to get to the root problem of the housing crisis for everybody.

“I actually think it’s a moral mission with the Labour government to recognise the problem and to build the social housing we need. I’ve been honest about not putting a figure on that today, because there’s a lot of moving parts within that. But hopefully at the spending review, you’ll see that this government is really serious that we’re going to build those houses we desperately need.

“It’s a moral mission for our government, and if it wasn’t, then what’s Labour for if we’re not building safe and secure homes that people need?”

With a combination of required targets for local authorities and significant changes to the planning system, Labour has pledged to increase housebuilding. However, experts predict that this won't be sufficient to fulfil the party's pledge to construct 300,000 additional homes annually, in part because the number of new planning permissions is at a 10-year low.

As per Shelter and other sources, ministers would require funding for 90,000 new social houses year in order to fulfil the goal. The charity discovered in a report earlier this year that doing so would come at a cost of £11.8 billion to the central government and an extra £23.6 billion from local governments or suppliers of social housing.

The charity argued the policy would pay back that investment within 11 years, and give an additional £12bn boost to the Treasury over 30 years.

Reeves is already under pressure to increase spending on several fronts, including by reversing the winter fuel payment cuts she announced in July. Unions are planning to bring a vote during conference condemning those cuts and calling on her to reverse them.

As part of her plans to boost social home provision in England, Rayner is also considering making it harder for tenants of council houses to buy their own home. Rayner bought her own council house using the right-to-buy scheme, but now argues that the discounts on such homes have become so steep that the housing stock is being depleted quickly.

“I’ve said that I’ll do a consultation on this, but the government, the changes that they made in 2012 means that more of our council homes are being sold off, and we just can’t replace them,” she said.