ION - Waterloo Region's Light Rail Transit

[Markster]

(a la 407, which strictly speaking wasn't a P3)

It quite was. It was a DBOM awarded to Canadian Highways International Corporation in 1994. (http://www.highway104.ns.ca/PRchic.pdf) Under an NDP government, no less.
It is accurate to say that the more controversial part of the 407, namely the 99-year lease in 1999, was not directly tied to its P3 genesis. Though, at the time, I don't believe people were happy about the (at the time) 35 years of tolls to pay for the financing of the highway.