Beresford pump on villiers MK 12 engine

I’m new to stationary engines so bear with me for obvious questions
I’ve recently acquired a Beresford water pump set to tinker with.First problem is how do you separate the pump from the motor shaft,I’ve undone all the obvious nuts but it won’t come of the shaft.Is it keyed on? Or on a taper even?l realise a few photos might help but I haven’t figured out how to do it yet

Hi and a warm welcome to the forum.  
You have a wait a day or so before you can post links/pictures.
Tutorial here:   https://ukengineforum.forumotion.com/t9665-how-to-upload-images

Hello and welcome!

I have a Beresford pump on it's own: https://ukengineforum.forumotion.com/t11399-beresford-pump

I will have a look at the manual to see if it gives any info.

The manual shows this set, but unfortunately only gives overhaul info for the pump unit itself.

From the pictures on your other thread I suspect that the engine has extended crankshaft with the impeller on the end.