The increased sentence for paedophile Sunderland spray painter Paul Leighton has been welcomed by police and the solicitor who led the case.
Leighton, 33, of Malvern Crescent, Seaham, had his jail term for a sickening string of sex offences increased from 16 years to 20 years by the Court of Appeal on Thursday.
Detective Inspector Angela Hufton, of Northumbria Police Safeguarding Department, said afterwards: "We are pleased by the decision from the Court of Appeal and satisfied with the increased sentence handed down to Leighton.
"This man had planned and carried out truly horrendous crimes against children over a sustained period. Many of his victims are still suffering the terrible results of his crime and will carry this burden with them throughout their lives.
"Leighton used a mobile phone to commit these offences and the cover of fake social media profiles to carry out this catalogue of abuse.
"Our officers worked with Homeland Security in the US as the devastating scale of his offences fully emerged during the investigation. This latest court case again shows just how vigilant young people and their families must be to stay safe against such calculated criminal activity.
"An important part of the work of our neighbourhood officers is to regularly visit schools to give advice to young people about staying safe online. We'd also ask parents and other family members to be vigilant and to remind them of the dangers of contacting strangers online and sharing indecent images.
"We hope the many families who have been victims of Leighton will now feel that justice has been done and will be able to start to move forward with their lives.
“The internet and social media should be a safe platform for young people but this type of offending highlights just how dangerous it can be.
“People need to be vigilant and aware of the risks because cowardly predators like Paul Leighton do hide behind their computer screen and target vulnerable people.
“This case shows to you that we will find these individuals, we will put them before the court and they will be put behind bars for a long time.
"Our work to safeguard people will continue and we would say to anyone suffering on-line abuse to contact police straight away and let us help you."
Solicitor General Robert Buckland presented the case at the Court of Appeal and said: “This is a deeply disturbing and serious case.
"Leighton callously targeted vulnerable children and subjected them to a series of threats, frightening them into complying with his sexual demands.
“Such terrible offending deserves a tougher punishment and this increased sentence takes into account the seriousness of this offending.”
Anyone who feels they have been a victim of a cyber-crime, or feels that they may have been groomed online, can contact police on 101 or Victims First Northumbria on 0800 011 3116.
Crime prevention advice about keeping safe online can be found on https://www.getsafeonline.org/