Janner: a Trial of the Facts is needed

Regarding the Janner scandal, on Facebook, a Guy called Dave Ismay says: 

Why is everyone ignoring the Trial of Facts option which was introduced into the 1991 Act expressly to deal with the unfit to plead dilemma ?

If the court determines that the accused is unfit to plead then a “trial of the facts” takes place before a jury. This was introduced by the 1991 Act and ensures that the evidence against the defendant is tested to some degree.

The jury now has to be “satisfied…the accused…did the act or made the omission charged against him as the offence” before the matter can proceed to disposal. The criminal standard of beyond reasonable doubt is used. If the jury is not so satisfied, they must acquit the defendant. The accompanying Government Circular to the 1991 Act states that the trial of the facts should not dwell on the defendant's intent (mens rea). Difficulties have arisen because to concentrate solely on the actus reus eliminates possible defences such as self‐defence yet to examine both the actus reus and mens rea makes the trial of the facts indistinguishable from a criminal trial

Criminal Procedure (Insanity) Act 1964 (the 1964 Act), as amended by the Criminal Procedure (Insanity and Unfitness to Plead) Act 1991 (the 1991)

This changes everything. Why did the CPS not go for this?