Abstract: A separator body 23 has a cylindrical internal surface 24 having an axis A arranged in use substantially horizontally. An inlet 19, 20 for a gas and liquid mixture, and respective outlets 53, 30 are provided in the body 23 for the liquid L and gas. The inlet 19, 20 is arranged such that the mixture leaving the inlet is directed substantially tangentially to the internal surface 24, whereby incoming mixture will travel circumferentially around the surface 24 to cause the liquid and gas to separate by centrifugal action. Catchment means 47 is provided which catches the liquid L travelling around the cylindrical internal surface 24 after separation of gas therefrom so as to direct the liquid toward its outlet 53.