The IWF 2016 Annual Report was published on 3 April 2017 and commendably is mostly primarily concerned with the removal and blocking of child abuse material. However the organisation also has a remit to censor adult porn .
The IWF report contains just a short section on this topic:
In 2016, 4,031 reports of alleged criminally obscene adult content were made to us. Almost all were not hosted in the UK, so they weren’t in our remit.
1 URL depicted criminally obscene adult content hosted in the UK received from a public source.