Rory, if you haven't read Ludlum, look at the above. Some of those books were written by other authors after his death.
I thought his best books were written by him in the 70's and 80's. I don't know if they now stand the test of time. I do remember really liking The Matarese Circle, Trevayne, The Osterman Weekend, Holcroft Covenant, and the Bourne books.
THE THOR EXIGESIS THE ZOOBA ASSIGNATION THE TALL INTERREGNUM THE MUTANT APOCALYPSE THE ESPINOZA EMPORIUM THE SONES MAELSTROM
Gee I really didn't think this would get so many replies. I was inspired after I wrote "the solium dialectic" in another post (a phrase which acutally does mean something) and realized it sounded Ludlumesque! bruce