This interesting piece of research from civet us suggests that the common conventional wisdom that the housing shortage is primarily caused by the planning system, may well be wrong.
It highlights the increasing discrepancy between the number of homes permissioned, and those built. it also points to the likelihood that the culprits are often neither planning departments nor many housebuilders, but speculative landowners.
However, one would note that the major house building firms are amongst the largest speculative landowners in business.
Whilst counting up the number of dwellings commissioned is likely to involve some over estimates (sometimes the same piece of land benefits from two or three separate permissions), the research does seem to indicate that planning departments are not the primary cause of our collective inability to build enough homes each year.
You can access the article here planning-approvals-vs-housebuilding-activity.