Out of my five ideas (spy hideout, mage's home, crashed ship, parkour circuit, and the turret defense) the spy hideout seems to have received the most positive attention. My original plan for the hideout involved basing it in the 1960s to 70s with secret rotating panels for equipment however after speaking with Alan it was clear that if I did not create a context or 'hook' for the hideout then it would just simply become an 'area'.
So I went about researching further into historical spies and espionage stories and that led me to two of the most famous spy rings the Portland Ring and the Cambridge Five (I guess they were only famous because there were so few spies exposed). The Portland Ring was led by a ladies man Russian spy by the name of Konon Molody and were passing information on naval weaponry to the KGB. It was the Cambridge Five ( Kim Philby, Donald Maclean, Guy Burgess, Anthony Blunt, and possibly John Cairncross) that caught my interest however as they were five British graduates of Cambridge University who loved their country, hated Fascism but also preferred the ideals of Communism.
My idea will be transferring from a spy hideout of the main character to a villain lair of the Cambridge Five and since they were from a privileged upper class the lair can venture into the eccentric. A combination of British architecture of manor houses with the stark contrast of Soviet Communist style. However since the Cambridge Five existed well into the 70s before they were exposed the house could also incorporate retro furnishings.
I will also be looking at art movements from those decades to further enrich the design of the lair.