A detailed account is given of the measurement of the radio-frequency radiation from the Great Nebula in Andromeda (M31) using a wave-length of 1.89 m. It is shown that the measured intensity is in good agreement with that to be expected on the assumption that the generation of the radiation is similar to that in the Galaxy. From these results it is estimated that the total extra-galactic radio emission amounts to about 1 per cent of the whole radio flux observed on the Earth.