The land on which Gatwick Airport stands was first developed as an aerodrome in the late 1920s. The Air Ministry approved commercial flights from the site in 1933, and the first terminal, 'The Beehive', was built in 1935. Scheduled air services from the new terminal began the following year. Major development work at the airport took place during the 1950s. The airport buildings were designed by Yorke Rosenberg Mardall between 1955 and 1988. In the 1960s, British United Airways (BUA) and Dan-Air were two of the largest British independent airlines at Gatwick, with the former establishing itself as the dominant scheduled operator at the airport as well as providing a significant number of the airport's non-scheduled services and the latter becoming its leading provider of inclusive tour charter services. Further rapid growth of charter flights at Gatwick was encouraged by the Ministry of Aviation, which instructed airlines to move regular charter flights from Heathrow. Following the takeover of BUA by Caledonian Airways at the beginning of the following decade, the resulting airline, British Caledonian (BCal), became Gatwick's dominant scheduled airline during the 1970s. While continuing to dominate scheduled operations at Gatwick for most of the 1980s, BCal was also one of the airport's major charter airlines until the end of the 1970s (together with Dan-Air, Laker Airways and British Airtours).