Thanks for that link... love those old books. I like to think that, should TMA archives survive in some way or another for the next 50-100 years future people might be able to say 'so that's what once existed at X farm before the farmer destroyed it in 2040'.
Re Maiden Castle... it is inconceivable that such a massive perimeter could ever have been defended in depth by the inhabitants so surely something else must have featured in the architects minds as well