Hi Rob
Yes CBC, ABC, and even BBC used some Presto equipment, look at my web page which has some information and links to other sources
http://canadianmilitarypattern.com/CBCandBBC.html and
http://canadianmilitarypattern.com/CBCandBBCinWWII.html. Now if your question is which model Presto thats going to take some researching.
I'm collecting information on Presto equipment of 1940's and 1950's. Presto was one of the big manufuactures of recording equipment. The US Navy equiped ships with disk recording equipment to record messages both Allied and Axis.
I'm also collecting Presto equipment which would have been in my truck. Recently I came across equipment list from BBC during WWII that listed them as having bought Presto Equipment. On the basis of this information I am willing to bet that my HUP would have been equiped with Presto gear.
Cheers Phil