Question: When did the roof gardens above Paul Bircher's birthplace open to the public?

full_context: Document 1: Paul Bircher: Bircher was born at Kensington, London. He was educated at Radley College and Christ's College, Cambridge and in 1948, he was a member of the victorious Cambridge crew in the Boat Race. Most of the Cambridge crew of 1948 also rowed for Leander Club at Henley Royal Regatta. The Leander eight were selected to row for Great Britain in the 1948 Summer Olympics and won the silver medal. Bircher was in the winning Cambridge crews in the 1949 and 1950 Boat Races. In 1953 he was a member of the Leander Club crew which won the Grand Challenge Cup at Henley Royal Regatta.
Document 2: Lucky de Chickera: Lucky de Chickera was educated at Royal College Colombo, being appointed the head prefectof Royal in 1965, and winning the most coveted Dornhorst Memorial Prize for outstanding merit in the same year. He went on to a successful career in the Corporate Private sector of the Country, that spanned 43 years of his working career until retiring as the Managing Director/CEO of Lanka Walltile PLC. Lucky was also an outstanding sports person representing his college in Rugby Football, and then going on to represent the Colombo school sides in 1963 and '64 and the Sri Lanka schools sides in both years. He continued his Rugby career into the Premier Rugby tournament of the Country by playing regularly for the CH&FC RUGBY CLUB one of the leading sides in Colombo from 1968 to 1971. He played for the Colombo clubs in 1968 and was a Sri Lanka trialist in 1968 and '69. He got married in 1969, and fathered three sons, who all went on to play representative rugby at school and junior country level.
Document 3: John Couchman: Couchman was educated at Christ Church, Oxford. In 1933, 1934 and 1935 he was a member of the losing Oxford boat in the Boat Races. In 1936 he was a member of the crew of the eight which came fourth representing Great Britain at the 1936 Summer Olympics in Berlin.
Document 4: Department store: All major cities have their distinctive local department stores, which anchored the downtown shopping district until the arrival of the malls in the 1960s. Washington, for example, after 1887 had Woodward & Lothrop and Garfinckel's starting in 1905. Garfield's went bankrupt in 1990, as did Woodward & Lothrop in 1994. Baltimore had four major department stores: Hutzler's was the prestige leader, followed by Hecht's, Hochschild's and Stewart's. They all operated branches in the suburbs, but all closed in the late twentieth century. By 2015, most locally owned department stores around the country had been consolidated into larger chains, or had closed down entirely.
Document 5: Kensington Roof Gardens: The building housed the department store Derry and Toms until 1973, and then Biba until 1975. Since the 1980s the garden has been used as a restaurant and club.
Document 6: Department store: The middle up segment is mainly occupied by Metro Department Store originated from Singapore and Sogo from Japan. 2007 saw the re-opening of Jakarta's Seibu, poised to be the largest and second most upscale department store in Indonesia after Harvey Nichols, which the latter closed in 2010 and yet plans to return. Other international department stores include Debenhams and Marks & Spencer. Galeries Lafayette also joins the Indonesian market in 2013 inside Pacific Place Mall. This department store is targeting middle up market with price range from affordable to luxury, poised to be the largest upscale department store. Galeries Lafayette, Debenhams, Harvey Nichols, Marks & Spencer, Seibu and Sogo are all operated by PT. Mitra Adiperkasa.
Document 7: Department store: All the major British cities had flourishing department stores by the mid-or late nineteenth century. Increasingly, women became the major shoppers and middle-class households. Kendals (formerly Kendal Milne & Faulkner) in Manchester lays claim to being one of the first department stores and is still known to many of its customers as Kendal's, despite its 2005 name change to House of Fraser. The Manchester institution dates back to 1836 but had been trading as Watts Bazaar since 1796. At its zenith the store had buildings on both sides of Deansgate linked by a subterranean passage "Kendals Arcade" and an art nouveau tiled food hall. The store was especially known for its emphasis on quality and style over low prices giving it the nickname "the Harrods of the North", although this was due in part to Harrods acquiring the store in 1919. Other large Manchester stores included Paulden's (currently Debenhams) and Lewis's (now a Primark).
Document 8: Dick Sale: Sale was born in Atcham, Shropshire, the son of Richard Sale who had also played cricket for Derbyshire. He was educated at Repton School and Oriel College, Oxford, and played for Oxford University in 1939 opening the batting in the University Match against Cambridge University, which Oxford won. In the same year he made his debut for Warwickshire in a match in which the only play was his opening partnership. The Second World War interrupted his academic and playing career, as he was commissioned in the King's Shropshire Light Infantry and served in Canada and Normandy. In 1946 he played again for Oxford University, and again Oxford won the Varsity match. He then finished the season playing for Warwickshire.
Document 9: Department store: The design and function of department stores in Germany followed the lead of London, Paris and New York. Germany used to have a number of department stores; nowadays only a few of them remain. Next to some smaller, independent department stores these are Karstadt (in 2010 taken over by Nicolas Berggruen, also operating the KaDeWe in Berlin, the Alsterhaus in Hamburg and the Oberpollinger in Munich), GALERIA Kaufhof (part of the Metro AG). Others like Hertie, Wertheim and Horten AG were taken over by others and either fully integrated or later closed.
Document 10: Arthur Lindsay Sadler: Sadler was born in Hackney, London. He was educated at Dulwich College, Merchant Taylors' School, London, and St John's College, Oxford (B.A., 1908; M.A., 1911). He was Pusey-Ellerton Hebrew scholar (1903), junior Kennicott Hebrew scholar (1907), won the junior Septuagint prize (1907) and graduated with second-class honours in Oriental languages (Hebrew and Assyrian).
Document 11: The Boat Race: The course covers a 4.2 - mile (6.8 km) stretch of the Thames in West London, from Putney to Mortlake. Members of both teams are traditionally known as blues and each boat as a ``Blue Boat '', with Cambridge in light blue and Oxford dark blue. As of 2018, Cambridge has won the men's race 83 times and Oxford 80 times, with one dead heat. Cambridge has led Oxford in cumulative wins since 1930. In the women's race, Cambridge have won the race 43 times and Oxford 30 times. Cambridge has led Oxford in cumulative wins since 1966. A reserve boat race has been held since 1965 for the men and 1966 for the women.
Document 12: Women's Boat Race: The course covers a 4.2 miles (6.8 km) stretch of the Thames in West London, from Putney to Mortlake. Members of both crews are traditionally known as blues and each boat as a ``Blue Boat '', with Cambridge in light blue and Oxford dark blue. As of 2018 Cambridge have won the race 43 times and Oxford 30 times. Cambridge has led Oxford in cumulative wins since 1966. The women's race has received television coverage and grown in popularity since 2015, attracting a television audience of 4.8 million viewers that year. The 2018 race was won by Cambridge by around seven lengths.
Document 13: Charles Littlejohn: Born in Nelson, New Zealand, on 4 January 1889, Littlejohn was the son of William Still Littlejohn and Jeannie Littlejohn (née Berry). He was educated at Nelson College from 1898 to 1903, and later went to New College, Oxford as a Rhodes Scholar (from Ormond College, Melbourne University) where he was a Diploma student in anthropology. He was a member of the winning Oxford crews in the Boat Race in 1911 and 1912. He was also a member of the New College eight which won the silver medal for Great Britain rowing at the 1912 Summer Olympics. He was subsequently decorated with the Military Cross while serving in World War I.
Document 14: Neues Schauspielhaus: While the auditorium was destroyed in World War II, the facade as well as the cinema survived and in 1951 was renamed the Metropol. Since 1977 it has been used as a discothèque and became a famous music club during the 1980s heyday of West Berlin, frequented by bands like Depeche Mode, Morrissey, The Cross, The Human League and Front 242. For a short time in 2000 it was the location of the KitKatClub and in 2005 the architect Hans Kollhoff remodeled the interior as the "Goya" night club.
Document 15: Plymouth: In 2004 the old Drake Circus shopping centre and Charles Cross car park were demolished and replaced by the latest Drake Circus Shopping Centre, which opened in October 2006. It received negative feedback before opening when David Mackay said it was already "ten years out of date". In contrast, the Theatre Royal's production and education centre, TR2, which was built on wasteland at Cattedown, was a runner-up for the RIBA Stirling Prize for Architecture in 2003.
ground_truth: 1980s
sub_queries: Paul Bircher >> place of birth Answer: Kensington
when did the roof gardens above Kensington open to the public Answer: 1980s