This BBC article seemed pretty occult to me. Perhaps they are subconsciously getting everyone to worship the Earth goddess Gaia (all the save Earth stuff on 7/7/07 and whatnot also show this new religion) by creating these by one of the main roads (leading to Oxford), one of them comes complete with a sun-cross nipple (below). They even found an excuse to get the old Wembley Twin Towers pictured because apparently large developments like its 'controlled demolition' (joke) dump their rubble and soil inside the "hills". Each tower also comes complete with a breast and nipple also.
Edit: Thought I'd throw this ultra symbolic cover of Ben Elton's new book in here too which I just saw advertised in The Times, see my post on Ferris wheels.