Found in an antique store what is it?

What is this tool? I found this in an antique store. I am new to wood working and am not familiar with it. The jaw next to the handle is freely movable the far jaw moves when you turn the wooden screw. Since the close jaw is moveable it doesn’t clamp down tightly. Both jaws stay aligned with through tenons. There is a little play in the screw but the mortices slide smoothly on the tenons with no play. Beautiful accurate work, I can see the layout lines of the mortices in the oak. Would like to have known the maker. What ever it is, it is of good quality. The booth where this tool is has old planes and molding planes as well which you can see in the background.