It's a very worrying situation and more research is needed on the most effective punishment and treatment of offenders caught viewing child abuse pictures.
"Trying to stop the terrible trade in these images is obviously a huge task.
"But it mustn't be seen in isolation. It's part of a much bigger sexual abuse problem."
More top news
As Princess Charlotte celebrates her first birthday on Monday, the young royal has received letters and gifts from 64 countries worldwide.
A 36-year-old man has been shot dead during a police operation in Kent.
Brussels' Zaventem Airport departure hall has reopened to the public, 40 days after twin suicide attacks killed 16 people.