The standard fibre optic reflectometer appears to have been overlooked as a means of making a fibre optic temperature sensor in favor of other more complex arrangements. The present sensor uses temperature induced variations of the refractive index of a captive volume of liquid at the end of an optical communications grade multimode fibre. The geometry of the sensing fibre tip is as simple as it is possible to imagine i.e. a flat, cleaved face, normal to the fibre axis. A short theoretical basis of the physics of the sensor will be presented. Systems constructed in both the 840 nm and 1300 nm wavelength regions are discussed. The linearity, noise characteristics, sensitivity, time response, temperature range and stability of these sensors have been examined.