As the only Toronto subway cars to be manufactured outside of Canada, its design was mainly influenced by the Q38 and R stocks of the London Underground. Since the TTC's original concept for the subway system foresaw the use of rapid transit cars derived from the President's Conference Car (PCC) design of its streetcar network, the cars were also equipped with bulls-eye incandescent lighting similar to that of a PCC, and a small operator's cabin located in the front left corner of each car. To this end, it was influenced by the 6000-series cars used on the Chicago "L", felt through the work of DeLeuw, Cather & Co. of Chicago, whom the TTC contracted as a consultant for the rapid transit project.