More photos.
I did a test fit on a Schwinn Varsity since it was handy. The extra bracket would bolt to the seat post clamp bolt. A wing bolt allows for deployment with out tools. There are 3 more thumb screws under the moveable cross bar. The two diagonal struts (wheel triangulation supports) get in the way so cross bar has to be moved all the way forward or back. I tried it both ways. At the rear, the strut ends stick out and could snag your legs or trousers. The cross bar movement is quite tight. Some WD-40 helped loosen it up some but it's still balky.
Upside down as suggested, it just collapsed to the ground. There are no locks on the main frame. The hinges have 180 degree stops built in to the main frame. There are 2 diagonal braces to the wheels that would get in the way too. The wheels are only 12" so it's pretty low to start with.
It can work as a rear rack for bags and panniers.
Rear axle attachment. Yes, the main arm (part number 3 in the diagrams described as "forked towing arm" in the patent application) should be free to swing up and down, both for the storing position and for riding over uneven terrain. For this particular bike It would need longer axles with a small collar and extra lock nut or double nuts. You would want less slop to minimize rattling and load shifting. Just bolting it under the axle nuts would be a problem. I see that happen quite often on the American Schwinn/Instep trailers that are improperly installed. Bolts above the axle could work depending on the dropouts. The Bob has pins that you remove to detach the trailer with no tools. That would make this far easier to attach when needed rather than leaving it on the bike all the time. With 2 wheels vs the Bob's 1 wheel, the connection doesn't need to be completely free of slop. There is room for mudguards on this 27" road bike.
The center thumb screw on the cross bar allow for the trailer to slide back about 6 or 7 inches for a longer tow bar. The tow bar is rather slender. I don't think it should be extended. Far to easy to bend it.
Missing 1 thumb screw on the cross bar. 6mm x 1 mm threads.
Overall it's rather futzy to deploy and store. I found it was much easier to fold up on a work table vs loosely mounted on the bike.
And what would I carry on it? Duffel bags? Large plastic storage box? I have other trailers that are functional without all the hassle of deployment. It's compact storage is it's main benefit. It's British heritage is good. Hum, a large wicker basket for picnic outings.
Loose test fit on a 27" road bike in the storage position
Cross bar stored at the front.
Panniers fit.
Room for mudguards on 27" wheels. Cross bar stored at the rear.
Upside down doesn't work. Also, tow bar fully extended.
Rear axle mount only practicable for more permanent installation.
Low to the ground on 12" wheels.