The apparatus includes a closure element 10, for use with a liquid container such as a beer barrel, the closure element having two apertures 15,16 and two associated closure members 30,31, the first aperture 15 being arranged to selectively allow air to be admitted to the interior of the container during a first procedure (e.g. cask conditioning), the second aperture 16 being arranged to allow a gas to be admitted to a bag 70 which in use expands to fill the container headspace as liquid is dispensed. The gas may be air at atmospheric pressure, or may be a pressurised gas. The apparatus may include an inner cap 20 which has an indented region 23 for locating the mouth of the bag using a rubber band 60 or the like. The closure members 30,31 may be interchangeable and the apertures may include with filter and sealing means 50.