The greatest savings were to be had in yard service, where switching often meant idling that maximized the efficiency advantages of diesel over steam.

It opened in 1950, eventually expanding several times to 208 acres (842,000 m2) and branching out into building transit buses, earth movers (Terex 1965-1980) and military vehicles built at adjacent facilities.

The first diesel locomotive built was Toronto, Hamilton & Buffalo Railway (TH&B) number 71, one of four model GP7 1,500 hp (1100 kW) road switchers.

It was however, not the first order (C-100) received, which was from Canadian Pacific for ten model FP7A 1,500 hp (1100 kW) A units of the "covered wagon" style of carbody.

For comparison, Alco 1,000 hp (750 kW) yard switchers built in Schenectady, New York cost $115,000 including import duty.

GMD built units for export, a significant amount of business supported by government grants to foreign countries.

With excess capacity at the London operation following the peak demand years of the 1950s, GMC Truck and Coach Division used it for production of heavy road vehicles such as buses.

Some primary equipment manufacturing, such as engines, generators, and traction motors, remained at EMD's LaGrange, Illinois facility.

[4] On April 4, 2005, GM sold its EMD subsidiary with its London and LaGrange operations to a partnership between Greenbriar Equity Group and Berkshire Partners.

[8] HCL Logistics moved into the plant space after consolidating their London operations and is partner with General Dynamics Land Systems in the same site.