In the novel The Floating Admiral, Billy is the barman at the Shades, a bar at the Lord Marshall, in Whynmouth. The bar is frequented by locals, such as fishermen.
Billy does not appear in person, but Mrs Davis mentions him when she is explaining how she heard about the murder of Admiral Penistone. She tells Inspector Rudge that she was there when Billy was taking down the shutters at the bar, and some ambulance men came in. She learned about the murder from them.