Herstmonceux Castle, the site of the Royal Greenwich Observatory (RGO) from 1948-1990. The RGO was moved from its initial site in London as light pollution in the city began to make observing difficult. In 1967, the 2.5 metre diameter Isaac Newton telescope (INT) was installed. Light pollution began to interfere with observations even in the East Sussex countryside, however, and in 1979 the INT was removed. It was installed at La Palma in the Canary Islands in 1984. With the INT gone, Herstmonceux became less important as an observational centre, and the RGO moved to Cambridge in 1990. Herstmonceux is now an education and exhibition centre.