Rocky, it says he was prosecuted and a 2 month custodial sentence, but it's because it's about the oldest woman. I have no idea why they didn't both get the same though.
I can't see why only she ended up on the sex offenders register. Surely he committed the same crime, if that's what it was.
I can't see why either of them had to be on the SOR anyway, with all its connations of paedophilia and rape. Neither of them did anyone any harm. Ok you don't want to see it while walking down the road, but surely a caution and fine would have been enough.