Columbia subject headings:
Transportation--England--London--History--19th century.
Transportation--England--London--History--20th century.
Harvard subject headings:
Local transit--England--London--History--19th century.
Local transit--England--London--History--20th century.
Transportation--England--London--History--19th century.
Transportation--England--London--History--20th century.
Princeton subject headings:
Transportation--England--London--History--19th century.
Transportation--England--London--History--20th century.