Who is Saul Dagenham from The Stars My Destination and what is their importance?

Saul Dagenham was a great physicist. Unfortunately, he suffered a terrible accident that left him extremely radioactive, leaving him unable to have physical contact with anyone for longer than five minutes, or even be in a room with them for longer than thirty minutes. The government pays Saul to stay away from others and to leave his own research alone. He builds a very successful jaunting courier business in the meantime. He partners with Presteign to torture the information they need out of Foyle. During his psychiatric manipulations, he introduces the idea of Geoffrey Fourmyle to him—an identity Foyle later assumes. He falls in love with Jisbella McQueen.