Bearing in mind the dramatic impact of radioastronomy upon our knowledge of the Universe during the years after World War II, it is remarkable that the seminal discovery of radio emission from our galaxy by Karl Jansky in the USA in 1931 attracted so little attention from the astronomical community at that time. It was, in fact, the radio amateur Grote Reber, of Wheaton, Illinois, and not the professionals, who first followed up Jansky's discovery. Designing his own radio telescopes, the first of which were unsuitable because the wavelengths were too short, Reber persevered until, in 1941, he successfully performed surveys of the distribution of radio noise intensity across the sky that indicated a strong concentration towards the galactic centre. In this country the key figure was J.S. Hey, who was engaged in wartime operational research concerned with anti-aircraft radar when, in February 1942, radar stations along the south coast of England were seriously affected by radio interference of unknown origin. From the direction of the interfering signals Hey concluded that the Sun must be responsible, so he contacted the Royal Greenwich Observatory and was informed that a large sunspot group was near the centre of the solar disc. He correctly deduced that some kind of disturbance in the solar atmosphere must have generated the radio signals, but this remained a wartime secret until the cessation of hostilities. Returning to his discovery in 1946, when the Sun was again active, Hey and his team made more detailed observations and showed that the intense bursts of radiation were often associated with solar flares. In the same year, while following up the work of Jansky and Reber, Hey noticed that radiation from the direction of the constellation Cygnus often showed fluctuations of intensity on a time-scale of a few seconds. With his experience of solar radiation, Hey deduced that a discrete source must have been responsible and more were soon located by other groups. Initially called radio stars, but later found to be supernova remnants, normal galaxies and new types of galaxy located near, or beyond, the limits of optical telescopes, Hey's discovery initiated an era of research that transformed observational astronomy. Such was the pace and excitement of this period that the significance of Hey's pioneering contributions tended to be overlooked. He was not proposed for Fellowship of The Royal Society until 1978, and he was elected in the same year.