What I don't understand about this is that his defence was that he believed them to be 16 and 17, however that would still have been just as illegal anyway. So he basically was admitting to the offence, just disputing the exact ages; how on earth was that a successful defence? He admitted he believed he was paying someone under 18 for sex, yet got off. I don't get it at all.
If they had been indeed 16, and he was done for that, and said "yeah I knew they were 16" he'd be going down, but because they were even younger he gets off. It makes zero sense.