Thorn accessory bar. Bag supported on rack.
Sure would like to do this on all my bikes, Brummie. Worked well enough on my frames where I could lay the bag's bottom atop the rack, but not on bikes where the needed vertical gap was unavailable (paralleogram suspension seatpost, see photo; bike model ended production in 2008, equipped with one of two Thorn Sherpa Mk2 forks in different rakes).
I love Thorn's T-bars and uplift, but tariffs make it impractical to equip every bike in my fleet!
As you might have guessed, this topic is near and dear to my heart...and my lightweight CCL camping setup...
https://thorncyclesforum.co.uk/index.php?topic=11787.msg85858#msg85858Best, Dan.