Bracket for mounting pannier rack to rear brake bolt

I could have sworn that I'd asked about this here already, but I can't find any sign of it, so here it is.

I have an old Dawes Galaxy. It doesn't have seat stay bosses to secure a pannier rack. The best option seems to be some sort of bracket that will use the rear brake bolt, and provide mounting points for a rack.

I have a rack already - it's just the bracket I need (otherwise I'll need to use P-clips I think). I previously made one; it broke.

I can't find such a bracket anywhere. Does anyone actually make such things? What are they called?

(A seatpost clamp with rack mount points won't work on this bike, so that's not an option.)

Something like this work?

https://www.sjscycles.co.uk/carriers-racks/14mm-tubus-clamp-set-rack-eyes-for-seat-stay-mounting/

Else large selection of random fixings here at SJS. I was looking for something similar and this was the best I came up with. https://www.sjscycles.co.uk/rack-spares/?order=price+ascending

I know you said you had a rack already, but the Blackburn AR-1 was a sturdy three-point rack mounting to the brake bridge that comes up on auction sights at reasonable prices. It would also look nice in a period-correct way on an older Dawes Galaxy.

I guess I can say goodbye to the paintwork under the Tubus clamps. At least they look like they won't be moving much.

And that AR-1 should be exactly what I need... are racks like that simply not made any more?

They don’t seem to be.
Often, they weren’t very good and tended to fracture at the bracket after a while. Also, as bikes moved away from calliper brakes to V and discs, there is no brake bridge to use.

I’ve got one of those racks for sale that mount to the brake boss.

Can post if you wanted it. https://www.lfgss.com/comments/16132311/

You could put some old inner tube underneath to stop the paint scuffing? Works wonders on a front rack that I’ve done the same way with no clips. Rubber helps with the grip so it doesn’t slip, tiny bit of vibration resistance for the bolts and protects the paint.