Oblomov I think the idea is that although many would think a phrase like "Fuck me harder" is pretty banal, it could apparently also be considered so distinctive that if two men claim that a woman uttered the phrase (or similar, anything including 'harder' will do), it can't possibly be a coincidence, they must be telling the truth. Being 'confident' in bed and having sex 'doggie style' are also identifying characteristics. No two (or three) men could possibly describe a woman having sex like this unless they had witnessed her having sex like this.
Somebody who says 'Fuck me harder' and has sex 'doggie style' must be an enthusiastic participant and can't have been raped. In these apparently exceptional circumstances, evidence from previous sexual partners can be used.
You might worry that Ched's description of the event had already been made public by the time these valiant guardian's of the truth came forward with this detail. You could argue that coming forward after all other legal avenues had been exhausted was a bit too much of a coincidence, certainly given the 'energetic' way that CE's friends, relatives and internet supporters attempted to defend him and that it appears that these witnesses were approached by CE's supporters even before they were interviewed by private investigators. To say nothing of the £50,000 reward on offer.
However, without proof that they were lying the Appeals court felt they had to allow the new evidence. Apparently 'Chinny reckon' isn't a legal term.
What we mustn't do is worry that anybody could use this kind of defence again except in very exceptional circumstances. 