John Gilbert Presslie Barnes is a British computer scientist best known for his role in developing and publicising the programming language Ada. He is the primary inventor of and protagonist for the Ada Rendezvous mechanism. Barnes studied mathematics at University of Cambridge and later worked at Imperial Chemical Industries (ICI). He was an industrial fellow at Wolfson College, Oxford in the very late 1970s or early 1980s, most likely at the suggestion of Professor Tony Hoare. Barnes was awarded an honorary Doctor of Philosophy (Ph.D.) from the University of York in 2006.