effective, continuous and unchallenged British possession and government for South Georgia was provided for by the British Letters Patent of 1843, revised in 1876, 1892, 1908 and 1917, with the island appearing in the Colonial Office Yearbook since 1887. From 1881 on, Britain regulated the economic activities and conservation by administrative acts such as the Sealing Ordinances of 1881 and 1899. South Georgia was governed by Britain as a Falkland Islands Dependency, a distinct entity administered through the Falkland Islands but not part of them in political or financial respect. These constitutional arrangements stayed in place throughout the second half of the 19th century and most of the 20th century, until South Georgia and the South Sandwich Islands were incorporated as a distinct British overseas territory in 1985. 20th century In the early 20th century South Georgia experienced a new rush of economic activity and settlement. Following a 1900 advertisement by the Falklands Government the entire island was leased to a Punta Arenas company, and a subsequent conflict of interests with the Compañía Argentina de Pesca which had started whaling at Grytviken since December 1904 was settled by the British authorities with the company applying for and being granted British whaling lease. South Georgia became the world's largest whaling centre, with shore bases at Grytviken (operating 1904–64), Leith Harbour (1909–65), Ocean Harbour (1909–20), Husvik (1910–60), Stromness (1912–61) and Prince Olav Harbour (1917–34). The companies involved included Compañía Argentina de Pesca, Christian Salvesen Ltd (UK), Albion Star (South Georgia) Ltd. (Falkland Islands), the Norwegian whaling companies Hvalfangerselskap Ocean, Tønsberg Hvalfangeri and Sandefjord Hvalfangerselskap, as well as the Southern Whaling and Sealing Company (South Africa). The Japanese companies Kokusai Gyogyo Kabushike Kaisha and Nippon Suisan Kaisha sub-leased respectively Grytviken in 1963–64 and Leith Harbour in 1963–65, the last seasons of South Georgia whaling. The spread of Norwegian whaling industry to Antarctica in the early 20th century motivated Norway, right after its independence from Sweden in 1905, to pursue territorial expansion not only in the Arctic claiming Jan Mayen and Sverdrup Islands, but also in Antarctica. Norway claimed Bouvet Island and looked further south, formally inquiring of the British Foreign Office about the international status of the area between 45° and 65° south latitude and 35° and 80° west longitude. Following a second such diplomatic démarche by the Norwegian Government dated 4 March 1907, Britain replied that the areas were British based on