CPS v P [2007] EWHC 946 (Admin)
(1) The fact that a court of 'higher authority' has previously held that a person is unfit to plead does not make it an abuse of process to try that person for subsequent criminal acts. The issue of the child's ability to participate effectively must be decided afresh. (2) Where the court decides to proceed to decide whether the person did the acts alleged, the proceedings are not a criminal trial (3) The court may consider whether to proceed to decide the facts at any stage. It may decide to do so before hearing any evidence or it may stop the criminal procedure and switch to the fact-finding procedure at any stage (4) The DJ should not have stayed the proceedings at the outset as he did without considering the alternative of allowing the trial to proceed while keeping P's situation under constant review. (5) If the court proceeds with fact-finding only, the fact that the defendant does not or cannot take any part in the proceedings does not render them unfair or in any way improper; the defendant's Article 6 rights are not engaged by that process.
The summary above is taken from the judgment (para 61) and could do with being "distilled" further.