There actually is enough housing, a lot of homes are empty, being used as 2nd homes etc.
There is enough room in London to build 500,000 new homes, but just not the sites that are cheap to buy and cheap to build on. This is more than enough to cover new housing needs several times over.
They also keep tearing down big blocks of flats in London, then sending the former residents to surrounding countries, artificially increasing the demand for new housing.
It’s just a ploy for rich developers and land owners to make tonnes of money, by pulling at the country’s heartstrings pretending they’re providing much-needed housing.
The fact that developers in previous decades destroyed green belt land doesn’t mean we should destroy what remains.