Jonathan Godson, aged 59, was caught by police after a sting operation by a paedophile hunting group called Confronted in Court.
Godson believed he was talking to a 13-year-old girl from Telford, called Ellie Harris, but was in fact talking to an adult woman who was part of the group.
Shrewsbury Crown Court heard that on February 14 last year Godson had gone to McDonald's in Donnington, where he believed he would meet the 13-year-old.
Instead, as he parked up opposite with his hazard lights on, a member of Confronted in Court approached the car and opened the door, at which point Godson drove off with his door still open.
The matter was reported to police, and then by chance, later that day the group recognised the same car driving on the M6, and called officers.
Godson, of Fyfield Road, London, was arrested and in an interview with police about the meeting said he had a "bad feeling about it", but "it was an itch he had to scratch".
He also told police he knew it was wrong, but add that it was "part of his nature".
During the conversations with the fictional girl, Godson had asked her about her sister, had discussed explicit sexual acts, and repeatedly asked her to switch on her camera phone.
He also said he would take her and her sister shopping, but not to tell her mother.
The court heard Godson had three previous convictions for a total of 29 offences.
They included possession of indecent images in 2003, and then possession of around 35,000 indecent images, for which he received a lengthy prison sentence in Jersey in 2013.
Paul Smith, mitigating, said his client had pleaded guilty to the offences
Sentencing, Judge Peter Barrie, said the offences were a "grave matter", and a "very serious escalation" from looking at images to trying to undertake physical abuse of a child.
He said: "Over your adult life it is clear you have shown persistent sexual interest in young children. In 2003 you were convicted in relation to possession of sexual images of children, in 2013 you were convicted of what must have been a very serious barrage of charges.
"When you were questioned by the police after they arrested you for this matter you explained to them in an interview you thought it was in your nature to have sexual interest in young girls.
"On this occasion you were using the internet, you were attracted to contact a person, which had in effect been uploaded by a child protection group, a member pertaining to be a 13-year-old girl.
"You engaged in conversation with her which became sexual. You arranged to meet her quite explicitly for sexual purposes."
He added: "It is a very serious escalation. A very grave matter. Not looking at or making images for the internet but actually arranging to meet, as you believed, a 13-year-old girl for these purposes."
The judge said he had no doubt that had Godson met a real 13-year-old girl then he would have committed the offences.
He said: "This first step into contact offending with young girls after the very many years in which you have shown this sexual interest in young girls is a very significant and worrying move, from looking at things on a screen to trying to meet a person for sexual activity to take place."
Judge Barry said it was clear Godson poses a "very serious risk to young girls".
Godson was jailed for a total of four-and-a-half years and will have an extended period of licence for fours years after release.
He was also made subject to an indefinite sexual harm prevention order.