Honestly I'm not sure - just going off an article I read recentlyHaven't several big builders gone under in recent times? My eldest is an apprentice bricklayer and has his sights set on Australia when he's done because the building trade is unstable in the UK.
Wouldn't surprise me if the medium-to-large companies are just being out competed by the super super big builders and slowly strangled - I know all the new estates being built onto my village are all like Taylor Wimpey, Barratt Redrow etc. nothing local or even regional, all big national ones