Who is Mr. Jones from No Longer at Ease and what is their importance?

Mr. Jones is Obi Okonkwo's fellow passenger aboard the HV Sasa from England to Nigeria, Jones is with the United Africa Company. He eats heartily but self-righteously refuses desert. Achebe contrasts him with the boat's chief engineer, who looks always on the point of seasickness at meals. Approaching Madeira, Jones quotes Jones quotes, "Water, water everywhere but not a drop to drink", from Samuel Taylor Coleridge's "The Rime of the Ancient Mariner".