I had a Carradice Junior saddlebag on the Brooks B17 on my old bike & thought it would be nice to move that bag over to my new Thorn Nomad, on which I have a Brooks Champion Flyer. The bag loops on the Champion Flyer seem to be a bit silly - those springs interfere with most saddlebags.
I just mounted an SQR bracket onto my seatpost & hung the Junior from that:
You can see that I have the saddle pushed back quite far on its rails. The back of the saddle is quite close to the front of the saddlebag. It looks to me like they won't collide as I bounce up and down in the saddle, but mileage and rough roads will tell.
I've seen a little bit of discussion about this combination out on the various bike forums, but nothing that seemed definitive. So here is one more report towards consensus.