Question: Commonwealth Railways DR class was a locomotive built by the industrial equipment manufacturer based in what city?

Context paragraphs:
Commonwealth Railways DR class: The DR class was a diesel locomotive built by Ruston & Hornsby for Shell in 1954.  Shell used it at their Clyde Refinery before it was sold in 1964 to the Commonwealth Railways.  It was withdrawn in 1975 and stored at Port Augusta until 1987 when it was sold to the Richmond Vale Railway Museum.

Commonwealth Railways NM class: The Commonwealth Railways NM class locomotive was a class of 4-8-0 locomotives of the Commonwealth Railways, Australia.  The class operated on narrow gauge lines in South Australia and the Northern Territory.

Ruston (engine builder): Ruston & Hornsby, later known as Ruston, was an industrial equipment manufacturer in Lincoln, England, the company's history going back to 1840.  The company is best known as a manufacturer of narrow and standard gauge diesel locomotives and also of steam shovels.  Other products included cars, steam locomotives and a range of internal combustion engines, and later gas turbines.  The company is now part of the Siemens group of Germany.

Commonwealth Railways G class: The Commonwealth Railways G class was a class of 4-6-0 tender locomotives of the Commonwealth Railways, Australia.  The class operated on the Trans-Australian Railway.

Commonwealth Railways NJ class: The NJ class are a class of diesel locomotive built by Clyde Engineering, Granville for the Commonwealth Railways for use on the Central Australia Railway in 1971.

Commonwealth Railways L class: The Commonwealth Railways L class was a class of 2-8-2 freight locomotives built in 1951-1952 by Clyde Engineering, Granville, for the Commonwealth Railways, Australia.

Commonwealth Railways C class: The Commonwealth Railways C class was a class of 4-6-0 passenger locomotives built in 1938 by Walkers Limited, Maryborough, for the Commonwealth Railways, Australia.

LNER Peppercorn Class A1 60163 Tornado: 60163 "Tornado" is a main line coal-fired steam locomotive built in Darlington, England.  Completed in 2008, "Tornado" was the first such locomotive built in the United Kingdom since "Evening Star", the last steam locomotive built by British Railways in 1960.  It is the only example of an LNER Peppercorn Class A1 locomotive in existence, the entirety of the original production batch having been scrapped without preservation.  The locomotive's namesake is the Panavia Tornado, a combat aircraft flown by the Royal Air Force.  As of April 2017, Tornado became the first steam locomotive to officially reach 100mph in over 50 years on British tracks.

Commonwealth Railways KA class: The Commonwealth Railways KA class was a class of 2-8-0 tender locomotives of the Commonwealth Railways, Australia.  The class operated on the Trans-Australian Railway.

Commonwealth Railways K class: The Commonwealth Railways K class was a class of 2-8-0 freight locomotives built in 1916 by North British Locomotive Company, United Kingdom, for the Commonwealth Railways, Australia.

Supporting paragraphs: Commonwealth Railways DR class Ruston (engine builder)
Answer: Lincoln, England