 In 1958 the Bristol 170 Freighter was added, followed by the Vickers Viscount in 1961.Further expansion in and out of London saw the introduction of the Hawker Siddeley HS 748 in 1962 and the Bristol Britannia in 1964.By the mid-1960s, London Heathrow had become BKS's busiest operational base with scheduled domestic flights to Leeds/Bradford, Teesside and Newcastle, as well as international scheduled services to Bilbao, Biarritz, and Bordeaux.