Okay so I'm almost 100% sure I saw this once..
There was this ad in a Dover Saddlery catalogue I believe it was.. Pretty sure it was around the seat saver section.
Anyway, there was this thing that you attach to the saddle that goes underneath the saddle like a saddlepad, but it had dee rings attached to it so you could attach bags and things to your english saddle.
Does anyone know where to find these? I've been looking all over but I haven't seen them since.