A review of Landsat MultiSpectral Scanner ‘Quicklook’ images in the National Remote Sensing Centre archive indicates that, on average, only one satellite pass in six over the United Kingdom results in cloud-free imagery. There are significant regional and inter-annual variations in acquisition of cloud-free imagery. Coastal districts are relatively less cloudy than inland upland areas, while the south-east of Britain and the western coast have the highest percentages of useful imagery. Inter-annual variations suggest that the chances of acquiring data from currently operational satellites within the precise date intervals required for automated crop mapping on a regular basis are very low. A wide range of other operational applications of remote sensing with less rigorous acquisition requirements are possible in the U.K. with current sensors. The study highlights the need for more frequent imaging by sensors of Thematic Mapper and SPOT HRV types, in order to minimize the effect of cloud cover and the longer-term requirement for development of all-weather microwave imaging systems of comparable spatial and spectral resolution to current optical sensors.