I think it's naive at this point to think Johnson is completely innocent. Nobody lets a case get this far if they can categorically disprove an accusation, I'm more than confident to say he's been involved with her in some capacity, it all just depends on whether she's fluffed the truth up to the point where she can rake in a load of extra cash. This is only my slant on it of course, I actually think he'll get away with it because a good barrister will pick apart any statement/testimony and rip the prosecution to pieces.
I've had first hand experience in being shredded by a barrister and it's the most uncomfortable place to be in, before she knows it, this girl or her representative could be demolished in front of a courtroom and the entire thing will start to look farcical. That's why some solicitors cost £50 per hour and others thousands of pounds.
I won't ever believe this guy is innocent, no matter what happens in that court room, because my judgement tells me he's a top of the range dickhead and the hat just seems to fit, very nicely.