It is right there in the section linked from the article:
(3) For the purposes of this section a person shall be taken to have shown that he was not in possession of a key to protected information at a particular time if—
(a)sufficient evidence of that fact is adduced to raise an issue with respect to it; and
(b)the contrary is not proved beyond a reasonable doubt.
... which makes me sad that misinformation is being used to fight a good cause.