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?

Context articles: MRT (Bangkok)
Taoyuan Metro
List of Bay Area Rapid Transit stations
London Underground
Fowler's Ghost
Johor Bahru–Singapore Rapid Transit System
Bay Area Rapid Transit
Chicago &quot;L&quot;
Taipei Metro
Rapid transit in Canada

The Metropolitan Rapid Transit or MRT is a rapid transit system serving the Bangkok Metropolitan Region in Thailand.
 The first section of the Blue Line between Hua Lamphong and Bang Sue opened in 2004 as Bangkok's second public transit system, while the MRT Purple Line opened in August 2016.
 The MRT is operated by the Bangkok Expressway and Metro Public Company Limited (BEM) under a concession granted by the Mass Rapid Transit Authority of Thailand ("MRTA").
 Along with the BTS Skytrain and the Airport Rail Link, the MRT is part of Bangkok's rail transportation infrastructure.
Taoyuan Metro (formerly Taoyuan Rail Transit and officially Taoyuan Mass Rapid Transit System) is a rapid transit system serving the Taoyuan City area in Taiwan.
 The proposed network will consist of five lines.
 The system opened for commercial service on March 2, 2017 with the opening of the Taoyuan Airport MRT.
Bay Area Rapid Transit (BART) is a heavy rail rapid transit system in the San Francisco Bay Area.
 It is administered by the San Francisco Bay Area Rapid Transit District government agency in three California counties: Alameda, Contra Costa, and San Francisco.
 BART is the fifth busiest rapid transit system in the United States, averaging between 433,000 and 455,000 weekday passengers by 2015.
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.
"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.
The Johor Bahru–Singapore Rapid Transit System (RTS Link) is a planned rapid transit system that would connect Singapore and Johor Bahru, Malaysia, crossing the Straits of Johor.
 The line is also referred to as the "Singapore-Johor Bahru Rapid Transit System", "Malaysia-Singapore Rapid Transit System", etc.
 If built, it would be the second rail link between the two countries, after KTM Intercity's North-South line, and the first designed for high-volume local transit.
 The first part of a preliminary engineering study was completed in March 2014, with the initial completion year targeted for 2019.
 However, according to Datuk Ismail Ibrahim, CEO of the Iskandar Regional Development Authority, completion date is targeted for 2022.
Bay Area Rapid Transit (BART) ( ), is a rapid transit public transportation system serving the San Francisco Bay Area in California.
 The heavy rail elevated and subway system connects San Francisco with cities in Alameda, Contra Costa, and San Mateo counties.
 BART operates six routes on 112 mi of track connecting 46 stations – this includes a 3.2 mi automated guideway transit line to the Oakland International Airport.
 A ten-mile spur line in eastern Contra Costa County will utilize a third set of rail technologies.
 With an average of 433,000 weekday passengers and 128.5 million annual passengers in fiscal year 2016, BART is the fifth-busiest heavy rail rapid transit system in the United States.
The Chicago "L" (short for "elevated") is the rapid transit system serving the city of Chicago and some of its surrounding suburbs in the U.S. state of Illinois.
 It is operated by the Chicago Transit Authority (CTA).
 It is the fourth-largest rapid transit system in the United States in terms of total route length, at 102.8 mi long, and the second-busiest rail mass transit system in the United States, after the New York City Subway.
Taipei Metro, Taipei Mass Rapid Transit or MRT, or the Taipei Rapid Transit System , is a rapid transit system serving metropolitan Taipei, Taiwan.
 The system is built by the Department of Rapid Transit Systems, Taipei City Government (DORTS-Taipei) and Department of Rapid Transit Systems, New Taipei City Government (DRTS-New Taipei) and operated by the Taipei Rapid Transit Corporation (TRTC).
 It consists of 108 stations (117 stations if transfer stations are double-counted) and 5 main routes and 2 branch lines, operating on 131.1 km of revenue track.
 The system carried an average of around 2.10 million passengers per day in March 2016.
There are three heavy rail and three light rail rapid transit systems operating in Canada.
 The Toronto subway was the first rapid transit system in Canada when it opened a 12-station line in 1954.
 It has since grown to encompass three heavy rail lines and one intermediate rail line and has the most number of stations of any system in Canada with 69.
 Construction has begun on the Eglinton Crosstown Line and the Toronto-York Spadina Subway Extension, which will add 28 new stations and a total of 27.6 km of new track.
 Montreal introduced the Montreal Metro in 1966 and has now become the most popular rapid transit system in the country with 1,263,800 daily riders.
 The Vancouver SkyTrain, an automated guided line, was opened in January 1986 for the Expo 86 world fair and is the longest rapid transit system in Canada with a system length of 79.6 km .
 There are three light rail systems operating in Canada including systems in Calgary (the CTrain), Edmonton (the Edmonton LRT), and Ottawa (the O-train).
 There is one light rail system under construction in Kitchener-Waterloo named Ion rapid transit.