I don't know about Jet Set Willy or Sabre Wulf, but a Java emulation of Sandy White's Ant Attack is available on the author's own webpage, http://www.sandywhite.co.uk/, along with a wealth of information about the game. I therefore assume that the game has now been placed into the public domain and so posting it here would not in fact be violating anyone's copyright.

It would still be a pretty stupid thing to do, however.