even after the merger, a British Airways European Division, which incorporated the former BEA Mainline operation, the erstwhile Super One-Eleven and Cargo divisions, as well as British Airtours, continued to exist alongside a British Airways Overseas, a British Airways Regional and four other divisions until 1 April 1977 when these were replaced by a unified operating structure organised into a number of departments, including commercial operations, flight operations, engineering, planning, catering and personnel. These organisational changes were accompanied by the adoption of a single, two-letter, IATA airline identification code for the entire airline, i.e., BA, the old BOAC/Overseas Division code. Until then, each of the three main airline divisions had its own two-letter, IATA airline identification code, BA for Overseas, BE for European and BZ for Regional. Highlands and islands operations Scotland The Dragon Rapides BEA had inherited from Scottish Airways and other former independent airlines it had taken over in early-1947 initially operated the corporation's Scottish routes, including services to remote communities in the Highlands and Islands. From 1948, BEA Dragon Rapides were contracted to operate the Scottish Air Ambulance Service. In 1952, BEA began replacing Dragon Rapides with Pionairs across its Scottish network; however, the pre-war de Havilland biplanes continued serving Barra as no other contemporary type in BEA's fleet could take off from and land on the island's beach airstrip. The Scottish Air Ambulance Service continued to contract BEA Dragon Rapides as well. Following successful trials of de Havilland's Heron Series 1 demonstrator G-ALZL on BEA's Channel Islands routes during the second half of 1951, the airline placed an order for two 1B series aircraft to replace "Islander" class Rapides on its Glasgow–Barra route as it was well-suited to serving restricted airfields in difficult weather conditions. Both aircraft were delivered in February 1955, wearing BEA's contemporary bare metal finish livery incorporating a burgundy cheatline separated by two thin, white lines above the cabin windows. In BEA service the Herons were known as "Hebridean" class aircraft seating 14 passengers on regular commercial flights. The Heron operated its first air ambulance service on 4 March 1955 while BEA crews were still undergoing conversion training on the new type. This was followed by a naming ceremony for both aircraft held at Glasgow's Renfrew Airport on 18 March 1955, when each aircraft was named after a Scottish medical pioneer (G-ANXA, the second aircraft to be delivered on 23 February 1955, was