"One-off?" Not sure if that particular builder, whoever it may have been, did more. The system's not unique, however. I've heard it referred to as cog drive.
There's one of these among the California Bicycle Museum collection. Those dropping in for the start of the Tour of California Stage 1 on February 15 can check it out in the display currently showing in Davis, California's "3rd & B" building. Here's a lovely profile shot:
<http://taps.ucdavis.edu/bicycle/resources/collection/actual/028-33493-2.jp g>
Dan Kehew Davis, California USA
On Wed, Jan 28, 2009 at 3:57 AM, Wyndham Pulman-Jones <simonpj@mac.com> wro
te:
> On French eBay, No: 320334382247
>
> A bike listed as from the 1940's, but must be considerably earlier. With
an extraordinary set up that replaces the chain and the drive-side chainsta
y with a huge cog directly joining the crank-mounted chainwheel and the dri
ve cog on the rear axle. Presumably all for the sake of drivetrain efficien
cy.
>
> Is this a one-off?
>
> Wyndham Pulman-Jones
> Girton, Cambs., UK.