A fetishist who spoke of molesting what he thought was a 12-year-old girl has been jailed for four-and-a-half years.

“Loner” Mathew Carlsson spoke of using sex toys on the girl, which he termed magic wands, and said he would support her financially. He played out his sick fantasies on web chatrooms and in a call to the “girl” and her mother.

Swindon Crown Court yesterday heard the 49-year-old had, in fact, been chatting to two undercover police officers, whose job it was to trawl the net for paedophiles.

Jailing the Lyneham man for four years and six months, Judge Jason Taylor QC said: “In the conversations generally you sexualised the topics, you went into graphic detail, you taught this young girl, about the role of a dominant daddy, saying you would look after her, that would include financial support, but also reassuring her as to your intentions.”

The court earlier heard Carlsson had swapped messages on website Chat Avenue with a woman last April. His username on the site was MattDDLG71, with the “DD” referring to “dominant daddy” or the father-daughter fetish he had. The conversation later moved to the Kik app.

The woman claimed to be 32, with a 12-year-old daughter. Carlsson described them both as “sexy” and spoke graphically of sexual acts he would like to perform on them, also talking about a dungeon. He claimed he had previously “owned” a girl of 12 to 14 and another older girl.

Prosecutor Caighli Taylor said Carlsson spoke to the girl on the phone, telling her the relationship of a “daddy don” and the daughter “was about experimenting and about the daddy don looking after the little girl”. He talked of having oral sex with the young girl.

He swapped messages with the woman, arranging to meet her and the girl in a hotel and sharing a meal. However, he stopped exchanging messages several days before the meeting was due to take place on April 25 in the east Midlands.

Carlsson was arrested in May. On his Lenovo tablet computer they found chat logs showing he’d sent a video via the Kik app of a child aged four to six being raped by a man. He had sent the video to a Kik user purporting to be aged 13 with a six-year-old sister. He also sent category C indecent images of children, which he falsely claimed to be his own children, to another Kik user. Also found on his device were three indecent films of children in category A, five category B images and 29 indecent images in category C.

Carlsson, of Church Farm Mews, Lyneham, pleaded guilty at the magistrates’ court to arranging the commission of a child sex offence, attempting to engage in sexual communication with a child, distributing indecent images and possession of indecent images.

Tony Bignall, mitigating, described his client as a lifelong loner, but had become more and more isolated since 2016. Although always holding down employment, he had turned increasingly to the internet for company.

He said Carlsson had not intended to act on the fantasies he had played out online. “It was just fantasy, certainly as far as Mr Carlsson was concerned. The contact he was enjoying was virtual. When it looked as if things might be heading towards an actual meeting he backed away.”

He had never been in trouble before and, since his arrest, had approached the Lucy Faithfull Foundation, a charity set up to rehabilitate sex offenders.

Judge Taylor jailed Carlsson for four years and six months, imposing a lifelong sexual harm prevention order and placing him on the sex offenders’ register for life.