I think it is Plaster though I'm really not sure if it is one piece or not, I think the stand is a separate piece, as is the base.
This weekend I will take it with me to my mothers where she has some white spirit and cotton buds and I will have a gentle go at some of the brush strokes.
Will also raid mother's sowing cupboard for a needle and gouge in a discrete place to determine the material.
Visually the brush strokes do not bother me too much, while there are some large ones on the front left breast that are overly noticeable, I am more apprehensive of simply ruining the pi