1)This was one of the first Doctor Who stories I ever saw, way back in the dim and distant era known as the 1970's - and I still find it quite watchable today, nearly forty years later.  Apparently it stemmed from Malcolm Hulke saying that the new "Earthbound" format for the show limited them to two kinds of stories - "Mad scientist" and "Alien invasion".   Terrance Dicks suggested that they coul…