SalvorHardin wrote: Instead I would be buying as much as I could realistically afford whilst keeping very quiet about it.
I think it likely that those profiting from rezoning of agricultural land keep a very low profile. It's something that local authorities could do and I suspect may have done in the past, namely to buy up such land and then give themselves permission to develop it.
For a totally speculative investment buying a piece of land large enough for development and sitting on it for years or decades might even make sense. The way the scam works is that someone had bought the land at a wholesale price. Rather than patiently wait for it to become more valuable they then up the price to finance salesman trying to con potential investors.
UK regulators may have prevented or strongly discouraged such schemes being marketed to UK based investors. Foreigners beware!