I feel like an idiot for asking, I got this question in a practice paper, it's the first question so it's easy. 
The question is "describe fully the single transformation that will map shape $P$ onto shape $Q$"
To me this is simply "Rotation $180^o$ about the point $(0, 1)$" However the mark scheme thinks it is $90^o$ clockwise?
Is there any way this could be true, it's not the first mistake in the mark scheme, but I need to be sure for my exam. (sorry if this question is to basic for here)
I assume that by "transformation" they mean "isometry" (else there would be infinitely many different transformations mapping these shapes onto each other).
The mark scheme is right; this is a rotation through $90^\circ$ clockwise, but about the point $(-2,3)$, not $(0,1)$. My grasp of what may have made you think it's $180^\circ$ is probably insufficient for me to say anything helpful about that, but in case you were focussing on the points at $(1,2)$ and $(-1,0)$, which are indeed related by a rotation through $180^\circ$ about $(0,1)$, note a) that these don't correspond to each other in the shapes and b) that no other pairs of points are related by this rotation.