I struggle to comprehend the numbers.
Yes so do I. The one in ten number isn highly suspicious, especially as the bit in the paywalled article that I could read also says
The results also showed that 5 per cent of British men had sexual feelings towards children and had acted upon those feelings
This contradicts the head line unless we are supposed to believe that 5% of British men do not have sexual feelings towards children, have not acted on those feelings and yet still admitted child sex offences.
I think it is likely that the survey is flawed or that the results are being misrepresented.