Question: What is the name of the designer of the locomotive used on the public rapid transit system serving London and some parts of the adjacent counties of Buckinghamshire, Essex and hertfordshire in the United Kingdom?

full_context: Document 1: Highbury &amp; Islington station: Highbury & Islington is a London Underground and National Rail interchange station in the London Borough of Islington, north London. It is served by the London Underground's Victoria line, London Overground's East and North London Lines, and Great Northern's Northern City Line.
Document 2: John Bull (locomotive): John Bull is a British-built railroad steam locomotive that operated in the United States. It was operated for the first time on September 15, 1831, and it became the oldest operable steam locomotive in the world when the Smithsonian Institution operated it in 1981. Built by Robert Stephenson and Company, the "John Bull" was initially purchased by and operated for the Camden and Amboy Railroad, the first railroad in New Jersey, which gave "John Bull" the number 1 and its first name, ""Stevens"". (Robert L. Stevens was president of the Camden and Amboy Railroad at the time.). The C&A used the locomotive heavily from 1833 until 1866, when it was removed from active service and placed in storage.
Document 3: History of public transport authorities in London: The history of public transport authorities in London details the various organisations that have been responsible for the public transport network in and around London, England from 1933 until 2000 and have used the London Transport brand. Their responsibilities have encompassed the buses, coaches, trams and the London Underground. The period began with the creation of the London Passenger Transport Board, which covered the County of London and adjacent counties within a 30-mile (48-km) radius. This area later came under the control of the London Transport Executive and then the London Transport Board. The area of responsibility was reduced to that of the Greater London administrative area in 1970 when the Greater London Council, and then London Regional Transport took over responsibility. Since 2000, the Greater London Authority has been the transport authority and the executive agency has been called Transport for London; ending the 67-year use of the "London Transport" name.
Document 4: London Overground: The London Overground (also known as the Overground) is a suburban rail network in the United Kingdom. Established in 2007, it serves a large part of Greater London and parts of Hertfordshire, with 112 stations on several routes. The network forms part of the National Rail network, but under the franchise control and branding of Transport for London (TfL). Operation has been contracted to Arriva Rail London since 13 November 2016.
Document 5: First Street Tunnel: The First Street Tunnel is a two-track, soft-earth tunnel built between 1904 and 1906 by the Washington Terminal Company to serve as the southern approach to Union Station in Washington, D.C. Currently owned by Amtrak, it connects to lower-level tracks and platforms at the station, passes under Capitol Hill and connects to the RF&P Subdivision (CSX Transportation) and Long Bridge, offering through railway service to Alexandria, Virginia, and points west and south. Unlike the Northeast Corridor tracks north of Union Station, the tunnel tracks are not electrified, so southbound trains leaving Union Station must switch to diesel locomotives before entering the tunnel. Exiting Union Station, the tunnel runs due south under First Street NE and SE before curving to the southwest under a parking lot near the Capitol South Metro station. Its southern portal is just east of South Capitol Street at the intersection of D Street SE and New Jersey Avenue SE.
Document 6: Northern line extension to Battersea: The Northern line extension to Battersea is an extension of the London Underground Northern line currently under construction from Kennington to Battersea in South West London, terminating at the redeveloped Battersea Power Station. The extension will form a continuation of the Charing Cross branch of the line. Two new underground stations will be built at Battersea Power Station and Nine Elms which will serve a new embassy district including, amongst others, the United States embassy and the Dutch embassy.
Document 7: Fowler's Ghost: "Fowler's Ghost" is the nickname given to an experimental fireless 2-4-0 steam locomotive designed by John Fowler and built in 1861 for use on the Metropolitan Railway, London's first underground railway. The broad gauge locomotive used exhaust recondensing techniques and a large quantity of fire bricks to retain heat and prevent the emission of smoke and steam in tunnels.
Document 8: List of metro systems: This list of metro systems includes electrified rapid transit train systems worldwide. In some cases, metro systems are referred to as "subways", "U-Bahns" or "undergrounds". s of October 2014 , 157 cities in 55 countries around the world host the approximately 160 metro systems that are listed here. The London Underground first opened as an "underground railway" in 1863 and its first electrified underground line opened in 1890, making it the world's first metro system. The metro system with the longest route length is the Shanghai Metro; the busiest one is the Beijing Subway; and the one with the most stations is the New York City Subway.
Document 9: Fireplace insert: Invented in 1896 by Joab R. Donaldson of Oliphant Furnace, Pennsylvania, US, the fireplace insert is a device inserted into an existing masonry or prefabricated wood fireplace. Joab was a 59-year-old coal miner and father of fourteen at the time of his patent. He came upon the idea as a means of using coke (a smokeless fuel made by the destructive distillation of certain types of coal) and incorporating the use of an electric blower to improve the efficiency. The selection of coke and coal tailings as a primary fuel enabled low income families to heat their Appalachian homes with small-size coal that they could easily dig for themselves in their own back yards.
Document 10: Puffing Billy (locomotive): Puffing Billy is the world's oldest surviving steam locomotive, constructed in 1813–1814 by coal viewer William Hedley, enginewright Jonathan Forster and blacksmith Timothy Hackworth for Christopher Blackett, the owner of Wylam Colliery near Newcastle upon Tyne, in the United Kingdom. It was the first commercial adhesion steam locomotive, employed to haul coal chaldron wagons from the mine at Wylam to the docks at Lemington-on-Tyne in Northumberland.
Document 11: Vienna U-Bahn: The Vienna U-Bahn (German: "U-Bahn Wien" ), where "U-Bahn" is an abbreviation of the German term "Untergrundbahn" (English: underground railway ), is one of the two rapid transit (metro) systems for Vienna, Austria. The second system is the Vienna S-Bahn. With the opening in October 2013 of the 4.2 km -, three-station extension of the U2 line, the five line U-Bahn network consists of 78.5 km of route, serving 104 stations. It is the backbone of one of the best performing public transport systems worldwide according to UITP (International Association of Public Transport) in June 2009. More than 1.3 million passengers rode the Vienna U-Bahn every day in 2009, and 567.6 million passengers used the U-Bahn in 2011, which declined to 428.8 million passengers in 2013. The network is undergoing expansion and rolling stock renewal. Since 1969, 200 million euros have been invested annually in the extension of the Vienna U-Bahn.
Document 12: History of the steam engine: The first recorded rudimentary steam engine was the aeolipile described by Heron of Alexandria in 1st-century Roman Egypt. Several steam-powered devices were later experimented with or proposed, such as Taqi al-Din's steam jack, a steam turbine in 16th-century Ottoman Egypt, and Thomas Savery's steam pump in 17th-century England. In 1712, Thomas Newcomen's atmospheric engine became the first commercially successful engine using the principle of the piston and cylinder, which was the fundamental type steam engine used until the early 20th century. The steam engine was used to pump water out of coal mines
Document 13: London Underground: The London Underground (also known simply as the Underground, or by its nickname the Tube) is a public rapid transit system serving London and some parts of the adjacent counties of Buckinghamshire, Essex and Hertfordshire in the United Kingdom.
Document 14: The London Game: The London Game is a British board game based on the London Underground in London, England.
Document 15: Watt steam engine: The Watt steam engine (alternatively known as the Boulton and Watt steam engine) was the first type of steam engine to make use of a separate condenser. It was a vacuum or "atmospheric" engine using steam at a pressure just above atmospheric to create a partial vacuum beneath the piston. The difference between atmospheric pressure above the piston and the partial vacuum below drove the piston down the cylinder. James Watt avoided the use of high pressure steam because of safety concerns. Watt's design became synonymous with steam engines, due in no small part to his business partner, Matthew Boulton.
ground_truth: John Fowler