Parsons gear pump

I just picked this up. Does anyone know anything about these like were they used for pumping water? Are they a good pump? What might it have been used for? etc etc.

I wouldn't say it was a bargain but it looks to be a well engineered piece of kit. Strange thing is, the casting that says parsons is upside down, which makes me wonder if this would have been mounted upside down on some bigger machine of some sort?