Trafalgar Square Authority in conjunction with the charity Unicef, who began ticketing the event to control crowd numbers. A Christmas ceremony has been held in the square every year since 1947. A Norway spruce (or sometimes a fir) is presented by Norway's capital city, Oslo as London's Christmas tree, a token of gratitude for Britain's support during World War II. (Besides war-time support, Norway's Prince Olav and the country's government lived in exile in London throughout the war.) The Christmas tree is decorated with lights that are switched on at a seasonal ceremony. It is usually held twelve days before Christmas Day.
Christmas tree cultivation and by the 1950s farmers were shearing and pruning trees to meet customer demands. The Christmas tree market burgeoned through the 1960s and 1970s, but from the late 1980s onward prices and the market for natural Christmas trees declined. In the early 21st century, nearly 98 percent of all natural (non-artificial) Christmas trees sold worldwide were grown on tree farms. Christmas tree farms are best located on relatively level land which is free of obstructions. In the past, Christmas tree farmers established their plantations on less desirable agricultural plots or "wastelands of agriculture". However, emphasis in modern Christmas tree farming