The UK Science and Engineering Research Council (SERC), through the Royal Greenwich Observatory (RGO), is installing on the island of La Palma, a 4.2 m altazimuth telescope, as part of the Observatorio del Roque de los Muchachos, at an altitude of 2300 m in the Canary Islands. The telescope, known as the William Herschel Telescope, is fully designed and manufacture has begun. It is due for completion in the mid-1980's. The telescope, dome and instrument design have all interacted with one another, particularly in the search for economy. Among the proposed instruments is a novel collimator-less spectrograph.