He suggested touching the decoy girl and filmed himself on Skype performing a sex act in their internet chats.
And he had 174 child abuse images and distributed 27 indecent pictures of children, in offences leading to a 16-month jail term.
He was released in October – but four days later he was back online making worrying inquiries about children, Teesside Crown Court heard.
He produced a phone and two tablets when his supervising officer made a first safeguarding visit to Jackson’s home.
He showed the officer a Facebook account in the name of Mark Johnson, said prosecutor Jenny Haigh on Monday.
Jackson said he created the profile after his conviction and had not registered it, as he was supposed to, because he forgot about it.
On the laptop he had been on a “just sex” forum under the anonymous pseudonym chatting to a young mum.
They exchanged sexualised messages and he received photos from the mum, a young adult.
He also contacted a user identifying herself as a mum, and the only question he asked was: “How old are your kids?”
And he communicated with a man calling himself “nakeddad”, asking only: “Kids with you?”
When asked to explain these queries, Jackson had no answer for police and said he needed to “work things out”.
Asked whether he had a sexual interest in children, he replied: “I don’t know why I asked those questions.
“I know it looks bad. I know it looks wrong.”
He said an iPhone seized from a holdall in his flat was defunct, he had bought it before his previous conviction and forgot about it.
Jackson, of Laurel Street, Middlesbrough, formerly of Redcar, admitted breaching a sexual harm prevention order and failing to comply with notification requirements.
He was jailed in January after admitting making and distributing indecent photographs of children, attempting to cause an underage girl to engage in sexual activity and attempting to cause her to watch a sexual act.
In January, he was described as a “recluse” with a long-standing depressive illness who would never have carried out his suggestions.
Years ago he had been vetted by social services with a view to becoming a foster parent.
In the latest case Nigel Soppitt, defending, said: “He was stressed and disorientated when he was released from prison and seems to have reverted to type.
“His lifestyle at that point was very chaotic. Upon his release he had 101 things to do.
“It’s a clumsy alias. It’s not the sort of alias that would deceive anybody.”
Since his arrest in October, he complied “enthusiastically” with his order prompting praise from his supervising officer, added Mr Soppitt.
Jackson was on medication for anxiety and depression and was having therapy and taking courses.
The Probation Service reduced his risk from high to medium and believed it could be managed in the community.
Mr Soppitt said: “He seems to be on the right path. I’d urge your Honour not to unsettle that.”
Judge Stephen Ashurst, however, told Jackson: “I am, I’m afraid, sceptical.
“Because of the speed at which upon your release you resorted to trying to make contact of a sexual nature in relation to your sexual interest in children.
“You said in something of an understatement ‘I know it looks bad, it looks wrong’.
“It was bad and it was wrong.
“You came out of prison and went on to these forums using a false name because plainly you have a sexual attraction to very young children.
“There is clear evidence of you using other adults online as effectively a route or a vehicle by which you could extend your interest in indecent images of children.”
He added there was a risk of serious harm, given the possibility of Jackson “trying to speak to like-minded adults”.
He jailed Jackson for a year, saying: “The courts have to be seen to be enforcing such orders.”
Grandpa sent sexual Skype to undercover cop posing as 14-year-old schoolgirl
A grandfather was caught chatting online to an undercover cop posing as an underage girl – and distributed child abuse images.
Brian Jackson, 50, was vetted by social services to become a foster parent years before he appeared shamefaced in court for his crimes.
Judge Peter Armstrong told him: “In 2018 you became involved in seeking sexual excitement or satisfaction through talking to what you thought was a young girl, 14 years of age.
“It was an undercover officer. Having made contact, the conversation became sexual.”
And he filmed himself on Skype performing a sexual act for her to see.
He was caught with devices containing 174 child abuse images – 47 at the most serious level – when he was arrested on May 24 last year.
“That’s bad enough,” said the judge.
“But you went on to distribute a number of those and others. That really is the most serious aspect of your case.”
Jackson distributed 27 pictures, three in the most severe category.
Jackson, formerly of Ennis Square, Dormanstown, Redcar, latterly living in Wiltshire, admitted eight offences.
They were two charges of making and three of distributing indecent photographs of children, two of attempting to cause an underage girl to engage in sexual activity and one of attempting to cause her to watch a sexual act.
Judge Armstrong said: “Immediate imprisonment is the only sentence that I can pass for your offending.”
Jackson was jailed for 16 months.
He was given a sexual harm prevention order banning him from unsupervised contact with under-18s and governing his internet and devices use, and will be on the sex offenders’ register, both for 10 years.