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

The Presteign is the head of the wealthy Presteign clan. He owns the Vorga and the Nomad, which are the two central space ships of the narrative. The first is the star ship that abandoned Gully Foyle to his fate aboard the destroyed second ship. The Presteign is also the owner of the volatile substance PyrE that can be detonated by Thought and Will.