Not exactly what you asked for, Ian, but...

Among my many projects on the burner is a DanneauxMade quick-release mount for *any* saddle rails.

I have some billet aluminum I plan to use to sandwich the saddle rails, clamped by a short (think seatpost collar) quick-release. The usual Carradice hardwood dowel will be reinforced on the outside of the bag with some half-round aluminum tubing (i.e. sectioned seatpost of handlebars...or replaced entirely eith tubing), secured through the lower billet clamp, tubing, bag fabric, and hardwood using longer bolts of the same diameter as original.

My goal here is to make my Carradice Camper Longflap mountable to virtually any saddle with exposed rails and, further, to make it quick-release de/mountable so I can take it quickly into a store with me while shopping or inside my tent to unload at my leisure if rain is bucketing down.

I've a few projects ahead of this one, but have assembled all the materials and it looks both simple and viable, which pushes for completion soonish.

Best, Dan.

Not tried it, but the Carradice Bagman Quick Release Expedition Saddlebag Rack doesn't require saddle loops.

Until recently I was using something with a similar function, a Lord Uplift, this used to be sold mail order (30-40 years ago) by the chap that made them.

Visible in the first photo in the thread below:

https://thorncyclesforum.co.uk/index.php?topic=12048.0
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A Carradice Camper Longflap will fit lengthwise on the top of a Thorn rear rack, but I haven't tried to fix a saddlebag to the rack in this position.

It would be easier to hang it off one side, and stabilise it with a strap round one of the rack struts.

But for me, the main point of using a traditional saddlebag is to avoid fitting a rack to the bike. If I have a rack I use pannier bags. Usually just one small one for day rides. For carrying more luggage I use two small, medium or large panniers depending on how much capacity I need.

With a stiff rack (Thorn or Tubus), I don't notice any difference in handling when carrying just one lightly loaded pannier bag.   

Bit of a domino effect this one.
Looking to change my B17 for something with a cut-out ( Sella SMP trek or similar )
This saddle does not have saddle loops but I can buy them from SJS.
Alternatively I was thinking about mounting the saddle bag longitudinally; along the length of the rack. There must be a work around. I wondered if anyone had tried. One advantage I thought of is that the load would be well supported on the rack and not ‘bounce around’ like it might do if conventionally mounted, even with the Carradice Bagnan support.
My aim is to have a lightweight touring ( none camping)  set up with the Camper Longflap, Ortlieb Ultimate bar bag and maybe a small frame bag.
TIA

It is the pump I usually don’t have…….

After to have tighten little the s
crew, the leather tor..

Is it normal ?

No. The rivets are very rusty, it looks like that saddle has been left outside in the rain for a long time.

I still have the first Brooks B17 saddle I bought in 1977. I mistreated that saddle by using too much neatsfoot oil too often, so it got soft and I stretched it more than I should have. The second photo shows where the rivets at the front have left a gap, the third photo shows how much I tightened the adjustment nut.

And the leather has worn so much that it is hardly possible to see the Brooks logo stamped on the side. But it is still rideable after 46600 kms, though not so comfortable as my other Brooks saddles.

It has been ridden "a lot" in the rain, but I nearly always use a cover (often just a plastic bag) when I leave the bike outside in rain, even for short stops. And as I used to use a traditional cycling cape, it rarely got completely soaked while riding. When it did get really wet I nearly always (not always possible on a long tour) made sure it dried out properly before storing the bike, to the extent that I (very occasionally) took it off the bike and brought it into the house to dry. 

My other Brooks saddles have been treated differently. I use a wax designed for care of leather boots (Nikwax or similar) on the saddle top about once every three months, depending on use. Plus very occasionally on the underside.

I still use neatsfoot oil bought from a horse accessories place, it probably has some kind of fungicide as an additif. Just a small amount on a rag to wipe saddles on the bikes that aren't getting used much in winter (mainly my wife's bikes), this is to stop or cure mould forming. 

The B66 Champion I bought in 1987-1988 is in better shape than my first Brooks saddle, despite having been ridden for over 70000 kms.