The Voorman Problem

Storyline: Doctor Williams is called in to examine the enigmatic Mr Voorman, a prisoner with a peculiar affliction: he believes he is a god. The Doctor must decide on the sanity of Mr Voorman - is he a faker or a lunatic? Diagnose him insane and they can ship him off to the asylum. But before making a decision, the Doctor has several questions in relation to Voorman's claims: why would a god choose to be straitjacketed in a prison, is there a way he can validate his boast and what has any of this got to do with Belgium?