The H series was the third series of rapid transit rolling stock used in the subway system of Toronto, Ontario, Canada. They were built in six production sets, named H1 to H6, from 1965 to 1990 in Thunder Bay, Ontario, for the Toronto Transit Commission (TTC). The first five sets were manufactured by Hawker Siddeley Canada until 1979, when the company was purchased by the Urban Transportation Development Corporation (UTDC), which then took over production. They operated alongside their predecessor models, the M series, while the H6 trains replaced the last remaining G-series trains in 1990. All H-series cars were manufactured in a facility Hawker Siddeley inherited from Canadian Car & Foundry, which had earlier produced PCC streetcars for the TTC's streetcar network. The facility was taken over by Bombardier Transportation in 1991, which has continued to produce all subsequent rolling stock for the subway. They include the successor of the H series, the T series, introduced in 1996 and which replaced earlier H-series (H1, H2, and the prototype H3) trains by 1999. The remaining H4, H5, and H6 trains were replaced between 2011 and 2014 by the newest model, the Toronto Rocket. History Based on the M1, the early H-series cars improved on the design, notably by enlarging the operator's cab and using a single-handle controller. Revisions were made to the designs, and each production model in the H series improved on the last. The H5s were the first subway cars in the TTC fleet to use chopper controls and were also the first cars with regenerative braking and air-conditioning systems. They had a brighter and more modern passenger interior. Black vinyl seats were replaced by red fabric seats. Individual seats replaced the padded bench seats used on previous models. The interior colour scheme consisted of red floors, cream walls, yellow doors and panels, and brown simulated wood grain panels. The H6s replaced the original red G-class cars and were used almost exclusively on the Bloor-Danforth line, with no further H-series orders made. The H6s were similar to the H5s, but had light brown floors, and orange doors and panels. A prototype T-series car was built by UTDC in 1990–1991, and evaluated by the TTC. By the time the TTC was ready to order new cars in 1992, UTDC had been sold to Bombardier. Bombardier added new technology such as AC propulsion to a platform based on the predecessor