There is an excellent e-book written by Wilfred Sergeant, available online, that details the history of the development of the GO Transit: Building GO Transit: The Rail Commuter Initiative of the Government of Ontario & Canadian National Railways. The Go Transit project started as a result of a 1962 GTA Transportation study.
One of the things I found interesting was how the name "GO" came about. At the time of its inception, the fashionable phrase was "go-go": go-go girls, everything a go-go. On top of that, the initials "GO" comprised a simple acronym for the Government of Ontario. As for the GO symbol, the letters, being round, represent the wheels of the train, and the intercepting lines, represent the T, hence GO Transit.
New Toronto was impacted by the inception of GO Transit, as the project team chose the Mimico Train Station for their service depot. The freight yard at Mimico Yards (in New Toronto) was at the time being vacated. While transfers and switchers would continue to operate in the CN Yards, much of the yard was available for other use. Unfortunately, the station itself could not be used as it was, because, at the time, it was being served by the CN Hamilton trains. The decision was made to build the depot on the east side of Royal York Road, off Judson Street facing Willowbrook Road. Hence, the name Willowbrook (after obtaining a release from CN, who actually had to rename one of their passing tracks in Northern Ontario in order to release the name Willowbrook).
To the left is the Willowbrook Yard in 1967. Other good sources of historical information on GO Transit are:
Go Transit's Lakeshore Line http://transit.toronto.on.ca/gotransit/2101.shtml
Go Transit - main website: www.gotransit.com