An apparatus for determining the identity and/or quantity of a liquid fuel contained in a fuel transporting tank of a fuel transporting vehicle, the tank having a headspace above a surface of the liquid fuel, the apparatus comprising: a longitudinally extensive member having a first end and a second end and a mounting arrangement configured for mounting, in use, of the longitudinally extensive member within and in fixed relation to the tank such that an immersion portion of the longitudinally extensive member extending upwardly from said second end is immersed in the liquid fuel in the tank, said longitudinally extensive member defining an internal volume from which liquid fuel in the tank is, in use, excluded, wherein said longitudinally extensive member further comprises: first and second pressure sensors spaced apart by a fixed distance, and each having a face exposed in use to the local hydrostatic pressure of liquid fuel in the fuel transporting tank, the respective first and second pressure sensors being configured to measure a pressure of the liquid fuel at a depth in the fuel transporting tank determined by their location and relative to a pressure of said internal volume of the longitudinally extensive member; a cover member arranged in confronting relation to an external surface of an upper portion of the longitudinally extensive member, the cover member and the said external surface defining therebetween a through passage extending from a local opening at a lower part of said cover member to an aperture formed at an upper part of said longitudinally extensive member by which aperture the internal volume is in communication with said through passage, the exterior of the longitudinally extensive member at the headspace and the internal volume communicating via said through passage and said aperture formed at an upper part of said longitudinally extensive member such that the pressure of the internal volume is the same as the pressure of the exterior of the longitudinally extensive member at the headspace, characterised in that the cover member is in the form of a skirt portion secured in fixed relation to an upper part of said longitudinally extensive member, said skirt portion surrounding said upper part of said longitudinally extensive member and wherein the through passage is in the form of a circumferential gap between an internal surface of the skirt portion and an external surface of the longitudinally extensive member, said circumferential gap being open to the exterior of the longitudinally extensive member at the headspace only at said local opening. first and second pressure sensors spaced apart by a fixed distance, and each having a face exposed in use to the local hydrostatic pressure of liquid fuel in the fuel transporting tank, the respective first and second pressure sensors being configured to measure a pressure of the liquid fuel at a depth in the fuel transporting tank determined by their location and relative to a pressure of said internal volume of the longitudinally extensive member; a cover member arranged in confronting relation to an external surface of an upper portion of the longitudinally extensive member, the cover member and the said external surface defining therebetween a through passage extending from a local opening at a lower part of said cover member to an aperture formed at an upper part of said longitudinally extensive member by which aperture the internal volume is in communication with said through passage, the exterior of the longitudinally extensive member at the headspace and the internal volume communicating via said through passage and said aperture formed at an upper part of said longitudinally extensive member such that the pressure of the internal volume is the same as the pressure of the exterior of the longitudinally extensive member at the headspace, characterised in that the cover member is in the form of a skirt portion secured in fixed relation to an upper part of said longitudinally extensive member, said skirt portion surrounding said upper part of said longitudinally extensive member and wherein the through passage is in the form of a circumferential gap between an internal surface of the skirt portion and an external surface of the longitudinally extensive member, said circumferential gap being open to the exterior of the longitudinally extensive member at the headspace only at said local opening.