The auction house selling this often sell so called plots of "amenity" land. It should be zoned as "green open space" in which case it should not be developed. In truth the low price suggests it won't get planning consent and caveat emptor applies. It is likely some unsuspecting innocent will buy a shedload of obligations leading to grief further down the line.
A single house plot in that area would realise many times the asking price!
Any resident who bought from the developer may want to take legal advice primarily to ask how their conveyancing lawyer got them into such a position.