Mixed trains on the CNR?

[RobertInOntario]

I don't have a definitive answer Rob, but I would guess that there were very, very few exceptions to this "rule". Placing the coach behind the engine would enable steam heating to be used, but would require either:
1) the coach to go through all the switching manoeuvres; or
2) the steam lines to be repeatedly disconnected and reconnected, along with the train line itself (for the brakes on all the trailing rolling stock), and an extra move or two at every stop to remove the coach from the middle of the consist.
For more info on so-called head-end cars in passenger trains being placed at the end of the train, look for doctorwayne's excellent posts from a while back about the various CNR head-end rolling stock. In short, the reason for head-end cars to be tail-end was ease and speed of switching upon arrival at their destination.
Hope that helps.
Andrew

Thanks, Andrew. All of this makes sense, especially re the switching reasons. I believe the British practise was also to run the freight cars behind the engine, with the passenger cars at the end -- again, based on the pictures I've seen.

Cheers, Rob