Here's a nice video from Flocasts with Greg McMillan, talking, initially, about Lydiard hill-work and the importance of working the downs as well as the ups.  Coincidentally, I came upon a more specific discussion of the workout from an article in  by Amby Burfoot.  There's more description from the Lydiard Foundation from Nobby Hashizume (who posts here frequently) and Lorraine Moller, with some video clips.