What is this tool designed for?

[Moby Duck]

I can see that it is a Vice but has anyone seen one like this and what would you think it was designed this way for?

I see it as an off set Vice but unusually it is off set to the left.
One hardened jaw only with a "V" notch to assist vertical clamping at the front but all of the alternative rear clamping shapes would be just as easily served with a "V" in the rear jaw for round objects..
The "V" notch is to the left of the main thread to allow long pipes etc to pass downwards and miss the thread, but it is not off set very far, indicating smaller diameter objects only.
I see a Square thread, not ACME so may not be commercially made although the old green paint on the threaded nut says otherwise.
No paint anywhere except the nut - why would anyone only paint the nut?
Initially it only appears to have one guide rail but one of the pics shows a second guide rail hiding under the main screw thread.
I see hacksaw marks on the right side rear jaw carriage which indicates someone has used it as an ordinary Vice and cut into the carriage when breaking through. (Bad design).
If you project an imaginary line between the front jaw "V" and the big "V" facing aft, (as pictured), you can derive an imaginary pivot point for the rear jaw that works fine for the large "V", but some of the other shapes seem like they wouldn't line up at all.
Some of the curved shapes on the rotating jaw look to have been duplicated and there doesn't seem to be a good reason for that, as only one can be used at a time.
If it so important to have a specific shape holding an object on the rear jaw then why is it then alright to hold the opposite side with an unshaped hardened jaw?
There is a strange looking spanner object attached to the right hand guide rail at the front - for some reason it isn't rusty. I have no idea what this spanner object could be for.
It is 170mm high at the front.