It's worse than simply having no strategic planning. Governments of all colours made plans not to allow housebuilding. It bugs me that Reeves said that in order to facilitate housebuilding, they would employ 30,000 more planning officers. This is bunkum - planning officers' primary effect is to stop houses being built, not to encourage them.
House prices rise because there aren't enough houses for the people that want them. (And also because such a lot of people have more money and can afford them.) If there are 50 houses for sale in the town and 100 people who want them and can afford to buy them, then they will start to outbid each other and prices would rise. If there were 100 houses for sale and 100 people to buy them, then prices wouldn't rise.
I reckon what they need to do is build some modern prefabs. Cheap and cheerful, mass produced, built off-site and assembled on the spot. It's the quickest way to provide more accommodation for the rapidly increasing population, while not affecting existing houses so badly that negative equity becomes epidemic. I dare say there would have to be complications like maximum shelf life or contributions to replacing them, short leaseholds, perhaps primarily to be used for social housing (ie. housing benefit), something like that. But we must have more houses.
George Clarke suggested something similar, wasn’t a factory with proper apprenticeships set up on Teeside? The Germans do this, with posh homes up to Passive House standard.