High resolution maps of every source in a statistically complete sample of 200 sources have been examined for common features. It is found that amongst the simple double sources the brighter component is, in nearly every case, closer to the associated optical object where one exists, is generally more compact than the fainter component and tends to have a flatter spectrum. Although the structures of the more complex sources are remarkably varied, they have many features similar to those of the simpler sources. The apparent association of complex structure with large physical size and low radio luminosity is shown to arise from observational selection effects. The radio emission from 95 per cent of the sources is concentrated along a narrow band on the sky which passes through the associated optical object if one is visible. The band is generally straight or smoothly curved. There appear to be no structural differences between quasars and radio galaxies.