So I bought a Thornward Dandy #4 from That Auction Site.
Here's a link to a picture of the camera.

The thing has a standard box camera rotary wedge shutter with the usual "Instant" and "Time" trips. However, on this guy there is a lever with three positions. McKeown's Guide and the seller said that the lever is a focus device.
I opened up the camera to clean, and discovered that the lens is fixed into a solid block of wood behind the stop wheel

The lever is connected to the shutter mechanism, as can be seen in this picture:

Can anybody provide information about what the purpose of the lever was? It doesn't really seem to do anything right now.