Question: When was prime minister first mentioned in a government document in the country that has the London museum that is prominently located in Trafalgar square?

full_context: Document 1: New Delhi: New Delhi is home to several historic sites and museums. The National Museum which began with an exhibition of Indian art and artefacts at the Royal Academy in London in the winter of 1947–48 was later at the end was shown at the Rashtrapati Bhawan in 1949. Later it was to form a permanent National Museum. On 15 August 1949, the National Museum was formally inaugurated and currently has 200,000 works of art, both of Indian and foreign origin, covering over 5,000 years.
Document 2: Royal Institute of British Architects: In 2004, the two institutions created the Architecture Gallery (Room 128) at the V&A showing artefacts from the collections of both institutions, this was the first permanent gallery devoted to architecture in the UK. The adjacent Architecture Exhibition Space (Room 128a) is used for temporary displays related to architecture. Both spaces were designed by Gareth Hoskins Architects. At the same time the RIBA Library Drawing and Archives Collections moved from 21 Portman Place to new facilities in the Henry Cole Wing at the V&A. Under the Partnership new study rooms were opened where members of the public could view items from the RIBA and V&A architectural collections under the supervision of curatorial staff. These and the nearby education room were designed by Wright & Wright Architects.
Document 3: England: English Heritage is a governmental body with a broad remit of managing the historic sites, artefacts and environments of England. It is currently sponsored by the Department for Culture, Media and Sport. The charity National Trust for Places of Historic Interest or Natural Beauty holds a contrasting role. 17 of the 25 United Kingdom UNESCO World Heritage Sites fall within England. Some of the best-known of these are: Hadrian's Wall, Stonehenge, Avebury and Associated Sites, Tower of London, Jurassic Coast, Saltaire, Ironbridge Gorge, Studley Royal Park and various others.There are many museums in England, but perhaps the most notable is London's British Museum. Its collection of more than seven million objects is one of the largest and most comprehensive in the world, sourced from every continent, illustrating and documenting the story of human culture from its beginning to the present. The British Library in London is the national library and is one of the world's largest research libraries, holding over 150 million items in all known languages and formats; including around 25 million books. The most senior art gallery is the National Gallery in Trafalgar Square, which houses a collection of over 2,300 paintings dating from the mid-13th century to 1900. The Tate galleries house the national collections of British and international modern art; they also host the famously controversial Turner Prize.
Document 4: Prime minister: Walpole always denied that he was "prime minister", and throughout the 18th century parliamentarians and legal scholars continued to deny that any such position was known to the Constitution. George II and George III made strenuous efforts to reclaim the personal power of the monarch, but the increasing complexity and expense of government meant that a minister who could command the loyalty of the Commons was increasingly necessary. The long tenure of the wartime prime minister William Pitt the Younger (1783–1801), combined with the mental illness of George III, consolidated the power of the post. The title was first referred to on government documents during the administration of Benjamin Disraeli but did not appear in the formal British Order of precedence until 1905.
Document 5: London: London contains four World Heritage Sites: the Tower of London; Kew Gardens; the site comprising the Palace of Westminster, Westminster Abbey, and St Margaret's Church; and the historic settlement of Greenwich (in which the Royal Observatory, Greenwich marks the Prime Meridian, 0° longitude, and GMT). Other famous landmarks include Buckingham Palace, the London Eye, Piccadilly Circus, St Paul's Cathedral, Tower Bridge, Trafalgar Square, and The Shard. London is home to numerous museums, galleries, libraries, sporting events and other cultural institutions, including the British Museum, National Gallery, Tate Modern, British Library and 40 West End theatres. The London Underground is the oldest underground railway network in the world.
Document 6: Kathmandu: The Srijana Contemporary Art Gallery, located inside the Bhrikutimandap Exhibition grounds, hosts the work of contemporary painters and sculptors, and regularly organizes exhibitions. It also runs morning and evening classes in the schools of art. Also of note is the Moti Azima Gallery, located in a three storied building in Bhimsenthan which contains an impressive collection of traditional utensils and handmade dolls and items typical of a medieval Newar house, giving an important insight into Nepali history. The J Art Gallery is also located in Kathmandu, near the Royal Palace in Durbarmarg, Kathmandu and displays the artwork of eminent, established Nepali painters. The Nepal Art Council Gallery, located in the Babar Mahal, on the way to Tribhuvan International Airport contains artwork of both national and international artists and extensive halls regularly used for art exhibitions.
Document 7: Micro gallery: A micro gallery was a computer-based guide to archives and museum collections, first developed for the collections at the National Gallery in London, UK It took three years to develop by the company Cognitive Applications, and opened in July 1991 as part of the facilities in the Sainsbury Wing. Visitors could use the system to determine which pictures they would like to see in the gallery. It was possible to print out personalised information for use during the visit. The Micro Gallery ran for 14 years and a CD-ROM with similar facilities was produced.
Document 8: Kathmandu: Kathmandu is home to a number of museums and art galleries, including the National Museum of Nepal and the Natural History Museum of Nepal. Nepal's art and architecture is an amalgamation of two ancient religions, Hinduism and Buddhhism. These are amply reflected in the many temples, shrines, stupas, monasteries, and palaces in the seven well-defined Monument Zones of the Kathmandu valley are part of a UNESCO World Heritage Site. This amalgamation is also reflected in the planning and exhibitions in museums and art galleries throughout Kathmandu and its sister cities of Patan and Bhaktapur. The museums display unique artifacts and paintings from the 5th century CE to the present day, including archeological exportation.
Document 9: Prime Minister of the United Kingdom: Prime Minister of the United Kingdom of Great Britain and Northern Ireland Royal Arms used by Her Majesty's Government Incumbent Theresa May since 13 July 2016 (2016 - 07 - 13) Government of the United Kingdom Office of the Prime Minister Style Prime Minister (informal) The Right Honourable (within the UK and the Commonwealth) His / Her Excellency (in international correspondence) Member of Cabinet Privy Council European Council British -- Irish Council Reports to Parliament Residence 10 Downing Street Chequers Seat Westminster Appointer Monarch of the United Kingdom Term length At Her Majesty's pleasure Inaugural holder Sir Robert Walpole as First Lord of the Treasury and de facto first Prime Minister. Formation 4 April 1721 Salary £151,451 annual, including £76,011 MP's salary Website Official website
Document 10: Prime minister: Canada's constitution, being a 'mixed' or hybrid constitution (a constitution that is partly formally codified and partly uncodified) originally did not make any reference whatsoever to a prime minister, with her or his specific duties and method of appointment instead dictated by "convention". In the Constitution Act, 1982, passing reference to a "Prime Minister of Canada" is added, though only regarding the composition of conferences of federal and provincial first ministers.
Document 11: Collection of the National Gallery, London: The National Gallery is the primary British national public art gallery, sited on Trafalgar Square, in central London. It is home to one of the world's greatest collections of Western European paintings. Founded in 1824, from an initial purchase of 36 paintings by the British Government, its collections have since grown to about 2,300 paintings by roughly 750 artists dating from the mid-13th century to 1900, most of which are on display. This page lists some of the highlights of the collection.
Document 12: Prime minister: The United Kingdom's constitution, being uncodified and largely unwritten, makes no mention of a prime minister. Though it had de facto existed for centuries, its first mention in official state documents did not occur until the first decade of the twentieth century. Accordingly, it is often said "not to exist", indeed there are several instances of parliament declaring this to be the case. The prime minister sits in the cabinet solely by virtue of occupying another office, either First Lord of the Treasury (office in commission), or more rarely Chancellor of the Exchequer (the last of whom was Balfour in 1905).
Document 13: London: London is home to many museums, galleries, and other institutions, many of which are free of admission charges and are major tourist attractions as well as playing a research role. The first of these to be established was the British Museum in Bloomsbury, in 1753. Originally containing antiquities, natural history specimens and the national library, the museum now has 7 million artefacts from around the globe. In 1824 the National Gallery was founded to house the British national collection of Western paintings; this now occupies a prominent position in Trafalgar Square.
Document 14: Prime Minister of the United Kingdom: Since the office evolved rather than being instantly created, it may not be totally clear - cut who was the first Prime Minister. However, this appellation is traditionally given to Sir Robert Walpole, who became First Lord of the Treasury in 1721.
Document 15: New Delhi: New Delhi is home to Indira Gandhi Memorial Museum, National Gallery of Modern Art, National Museum of Natural History, National Rail Museum, National Handicrafts and Handlooms Museum, National Philatelic Museum, Nehru Planetarium, Shankar's International Dolls Museum. and Supreme Court of India Museum.
ground_truth: first decade of the twentieth century
sub_queries: Which London museum is prominently located in Trafalgar Square? Answer: the National Gallery
the National Gallery >> country Answer: UK
When was prime minister first mentioned in a government document in the UK ? Answer: first decade of the twentieth century