Does anyone have a photo of how the rear portion of the rear seat of a 1927 AD tourer attaches to the body. Is a frame involved ?

Ken,

if you are taking about the the upright part of the seat, as apposed to the base, it is simply a flap.

The top is help in place under the aluminium strip along the top of the body.

The rear cushion has a wooden base with a spring frame, top covered in felt, and whole has rexine cover nailed to the underside of the wooden frame. At the front underside of the wooden frame there is a 'lazy S' metal strip either side which clip under the return at the top of the floor pan rear seat support. To fix in place lower cushion in front first and make sure 'lazy S' clips are in place then lower the rear of the cushion. This keeps the cushion in place. There is a small piece of leather approx 3" x 1" nailed either side of the wooden frame which rest on the return.

Thank you for your reply. I did mean the rear portion Ruairidh, --What holds the bottom, or does it just hang from the top rail? and does it require thin plywood back like the Ruby ?

The ones have seen just hang down and the seat base holds it in place. I have never found any plywood personally.

Rauiridh is quite right the rear seat back just hangs down and is only held in place at the bottom by the seat cushion. There is no plywood. My AD Chummy has its original upholstery and it is just like that. One could argue that the two hood bag straps do hold the seat back in place as well. The seat back is made from a rexine outer and a rough cloth inner, machined together vertically to form the flutes. These are stuffed with horse hair.