Bradley Baker falsely told his ex-partner, family and friends that he worked for the British Transport Police.
The 28-year-old from Birmingham first came to the attention of officers after North Wales Police received a report linking him to a separate offence.
He was reported as a serving BTP special constable based in Birmingham, but it was soon established that Baker had never worked for the force.
He was arrested after police raided his home in Kenilworth Road and seized numerous items of police uniform including a warrant card badge and holder displaying ‘DC Baker’, two fake BTP warrant cards, and several police lanyards.
Baker tried to throw his laptops out of a window as officers arrived but several unregistered laptops and devices were also found which showed he had breached a Sexual Harm Prevention Order that any electrical device in his possession must be registered with police.
That order had been handed to him after he committed three sex offences involving children in 2018.
A laptop which was later found to be stolen from his previous job as a journalist was also recovered, as well as cannabis.
Baker pleaded guilty to possession of police articles, theft by employee, two counts of possession cannabis and two counts of breaching the Sexual Harm Prevention Order.
He was sentenced to 28 months in prison at Birmingham Crown Court on Friday.
Jade Ledbrook, a constable at BTP, said: “Possessing fake items of police uniform and posing as a police officer is an extremely serious offence, and I’m glad that the severity of Baker’s delusional actions is reflected in his sentence.
“Sexual Harm Prevention Orders are given to protect the public, and Baker’s blatant disregard for this demonstrates his dangerous mindset.
“Had he not been stopped as a result of this extensive investigation, he could have continued to commit even further, and potentially more serious, crimes.
“Therefore I’m pleased to see him behind bars.”