It's a kimbewicke. Primarily a English bit, and no longer a legal bit for hunters. (Hooray!) It's a leverage bit, with a curb chain. Usually ridden with one rein, so limited flexibility and can be very punitive. Lacks the flexibility of a pelham or a three ring snaffle.
I actually like it better as a western bit, ridden with limited contact; than an english bit.
Pretty much consistent with the condition of the horse and the rest of the tack.
PS - Sigh. Just looked at the photos again and the curb chain is twisted. Sigh. Poor horse.