No, emmie it may be you have not got how planning works/ worked. If I wanted to build an estate, however small,, I would have to build affordable housing, very cheap and small homes, at the same time. The ratio varied from council to council. This council required one for one. The adjacent council required one affordable in three. Without undertaking to build the affordable, I wouldn't get permission for any houses at all. This policy meant that I might be able to build one house alone, however much it would sell for, be it £300,000 or £3 million or £30 million, but I couldn't build two without one being affordable and on the same site.
Developers building vast estates would build the affordable last, to get the standard ones sold, then build the affordable in a separate part of the estate, so as not to have cheap next to dear.
This policy is supposed to have been relaxed. People weren't building houses, for one thing. But it lingers on.