Comment by tialaramex

More houses would actually improve affordability, because it would increase supply obviously - but as we see while announcing such a programme is popular, implementing it is not. Thus Tories like to announce big house-building programmes slightly before an election - look at all these houses we're building. After the election when it comes time to actually figure out where all these houses would go (many BANANA†s are Tory voters), the programme is back-burnered or entirely eliminated, then it can be resurrected for the next election. So this announcement basically only signals Boris does not intend to hold an election very soon.

† Build Absolutely Nothing Anywhere Near Anyone/Anything