thanks for the plug Andy, although I am afraid that thread is a bit rambling even by my standards!
I summarised the little I could find about the Entwisle and Kenyon vices
here.
The part above looks like the toothed block from their "instantaneous grip" woodworkers vice (I confess I did not know they made any other kind).
No idea on value I'm afraid - there do not seem to be many survivors. I am sure there are people who will be interested from a historical perspective but better designs were invented not long after it was made, so you are probably going to need to find a vice geek to sell to
please post some more pics if you have time!