Question: In which year did the publisher of Roald Dahl's Guide to Railway Safety cease to exist?

full_context: Document 1: Railtrack: Railtrack was a group of companies that owned the track, signalling, tunnels, bridges, level crossings and all but a handful of the stations of the British railway system from 1994 until 2002. It was created as part of the privatisation of British Rail, listed on the London Stock Exchange, and was a constituent of the FTSE 100 Index. In 2002, after experiencing major financial difficulty, most of Railtrack's operations were transferred to the state-controlled non-profit company Network Rail. The remainder of Railtrack was renamed RT Group plc and eventually dissolved on 22 June 2010.
Document 2: Rhyme Stew: Rhyme Stew is a collection of poems for children by Roald Dahl, illustrated by Quentin Blake. In a sense it's a more adult version of "Revolting Rhymes".
Document 3: The Great Book of Ireland: Working to the supervision of Scott, Brown provided the endlessly inventive scripts which lace through the Book. Pages shuttled back and forth across Ireland, over to Britain, Germany and France, to an artist on expedition inside the Arctic Circle; pages were brought to poets, groups of poets came to make their contributions; the pages accumulated, but pages need to be bound into a book.
Document 4: Railtrack: Railtrack was a group of companies that owned the track, signalling, tunnels, bridges, level crossings and all but a handful of the stations of the British railway system from 1994 until 2002. It was created as part of the privatisation of British Rail, listed on the London Stock Exchange, and was a constituent of the FTSE 100 Index. In 2002, after experiencing major financial difficulty, most of Railtrack's operations were transferred to the state - controlled non-profit company Network Rail. The remainder of Railtrack was renamed RT Group plc and eventually dissolved on 22 June 2010.
Document 5: The Red Tree (Shaun Tan): The Red Tree (2001), written and illustrated by Shaun Tan, is a picture book that presents a fragmented journey through a dark world. The illustrations are surreal. The text is sparse and matches the dark illustrations.
Document 6: Roald Dahl bibliography: During the Second World War Dahl was a pilot in the Royal Air Force (RAF) until he crashed in the Libyan desert; the subsequent injuries left him unfit to fly. He was posted to Washington as an assistant air attaché, ostensibly a diplomatic post, but which also included espionage and propaganda work. In 1942 the writer C.S. Forester asked him to provide details of his experiences in North Africa which Forester hoped to use in an article in The Saturday Evening Post. Instead of the notes which Forester expected, Dahl sent a finished story for which he was paid $900. The work led to The Gremlins, a serialised story in Cosmopolitan about a mischievous and fictional RAF creature, the gremlin; the work was published as Dahl's first novel in 1943. Dahl continued to write short stories, although these were all aimed at the adult market. They were sold to magazines and newspapers, and were later compiled into collections, the first of which was published in 1946. Dahl began to make up bedtime stories for the children, and these formed the basis of several of his stories. His first children's novel, James and the Giant Peach, was published in 1961, which was followed, along with others, by Charlie and the Chocolate Factory (1964), Fantastic Mr Fox (1970), Danny, the Champion of the World (1975), The BFG (1982) and Matilda in 1988.
Document 7: London Passenger Transport Board: The London Passenger Transport Board (LPTB) was the organisation responsible for local public transport in London and its environs from 1933 to 1948. In common with all London transport authorities from 1933 to 2000, the public name and brand was London Transport.
Document 8: Railway Recruitment Control Board: Railway Recruitment Boards are organisations under the Government of India that manage the appointment of new employees to work in Indian railways. There are 21 boards situated in different parts of India:
Document 9: The Giraffe and the Pelly and Me: The Giraffe and the Pelly and Me is a 1985 children's book written by Roald Dahl and illustrated by Quentin Blake. It is about a young boy, Billy, who meets a giraffe, pelican and monkey who work as window cleaners.
Document 10: British Railways Board: The British Railways Board (BRB) was a nationalised industry in the United Kingdom that operated from 1963 to 2001. Until 1997 it was responsible for most railway services in Great Britain, trading under the brand name British Railways and, from 1965, British Rail. It did not operate railways in Northern Ireland, where railways were the responsibility of the Government of Northern Ireland.
Document 11: British Rail sandwich: The British Rail sandwich has been used as a negative point of comparison for other ready-to-serve meals, especially regarding transportation in the United Kingdom, and representative of the negative effects of British nationalisation of industry in the middle of the 20th century. A 1997 article in "The Independent" referred to the sandwich as "an indictment of statist, bureaucratic corporations" privatised by Prime Minister Margaret Thatcher, who had "swept aside James Callaghan, prices and incomes policies and the British Rail sandwich".
Document 12: The Vicar of Nibbleswicke: The Vicar of Nibbleswicke is a children's story written by Roald Dahl and illustrated by Quentin Blake. It was first published in London in 1991, after Dahl's death, by Century. The protagonist is a dyslexic vicar, and the book was written to benefit the Dyslexia Institute in London (now Dyslexia Action), with Dahl and Blake donating their rights.
Document 13: Roald Dahl's Guide to Railway Safety: Roald Dahl's Guide to Railway Safety was published in 1991 by the British Railways Board. The British Railways Board had asked Roald Dahl to write the text of the booklet, and Quentin Blake to illustrate it, to help young people enjoy using the railways safely.
Document 14: History of rail transport in Great Britain: The railway system of Great Britain, the principal territory of the United Kingdom, is the oldest in the world. It was started with the building of local isolated wooden wagonways starting in 1560s. The system was later built as a patchwork of local rail links operated by small private railway companies in late 18th century. These isolated links developed during the railway boom of the 1840s into a national network, although still run by dozens of competing companies. Over the course of the 19th and early 20th centuries, these amalgamated or were bought by competitors until only a handful of larger companies remained (see railway mania). The entire network was brought under government control during the First World War and a number of advantages of amalgamation and planning were revealed. However, the government resisted calls for the nationalisation of the network. In 1923, almost all the remaining companies were grouped into the ``big four '', the Great Western Railway, the London and North Eastern Railway, the London, Midland and Scottish Railway and the Southern Railway. The`` Big Four'' were joint - stock public companies and they continued to run the railway system until 31 December 1947.
Document 15: Matilda (novel): Matilda is a book by British writer Roald Dahl. It was published in 1988 by Jonathan Cape in London, with 232 pages and illustrations by Quentin Blake. It was adapted as an audio reading by actress Kate Winslet, a 1996 feature film directed by Danny DeVito, a two - part BBC Radio 4 programme starring Lauren Mote as Matilda, Emerald O'Hanrahan as Miss Honey, Nichola McAuliffe as Miss Trunchbull and narrated by Lenny Henry, and a 2010 musical.
ground_truth: 2001
sub_queries: Roald Dahl's Guide to Railway Safety >> publisher Answer: British Railways Board
In which year British Railways Board ceased to exist? Answer: 2001