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?

<P0-S0> 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. <P0-S1> The first of these to be established was the British Museum in Bloomsbury, in 1753. <P0-S2> Originally containing antiquities, natural history specimens and the national library, the museum now has 7 million artefacts from around the globe. <P0-S3> 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. <SEP> <P1-S0> pradhan mantri jeevan jyoti bima yojana is a government - backed life insurance scheme in india. <P1-S1> it was originally mentioned in the 2015 budget speech by finance minister arun jaitley in february 2015. it was formally launched by prime minister narendra modi on 9 may in kolkata. <P1-S2> as of may 2015, only 20% of india's population has any kind of insurance, this scheme aims to increase the number. <SEP> <P2-S0> the prime minister of canada (french: premier ministre du canada) is the primary minister of the crown, chairman of the cabinet, and thus head of the government of canada, charged with advising the canadian monarch or federal viceroy on the exercise of the executive powers vested in them by the constitution. <P2-S1> not outlined in any constitutional document, the office exists only as per long - established convention (originating in canada's former colonial power, the united kingdom) that stipulates the monarch's representative, the governor general, must select as prime minister the person most likely to command the confidence of the elected house of commons; this individual is typically the leader of the political party that holds the largest number of seats in that chamber. <P2-S2> canadian prime ministers are styled as the right honourable (french: le très honorable), a privilege maintained for life. <SEP> <P3-S0> The United Kingdom's constitution, being uncodified and largely unwritten, makes no mention of a prime minister. <P3-S1> 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. <P3-S2> Accordingly, it is often said "not to exist", indeed there are several instances of parliament declaring this to be the case. <P3-S3> 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). <SEP> <P4-S0> 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. <P4-S1> Visitors could use the system to determine which pictures they would like to see in the gallery. <P4-S2> It was possible to print out personalised information for use during the visit. <P4-S3> The Micro Gallery ran for 14 years and a CD-ROM with similar facilities was produced.