Astonishingly, after learning that the 'girl' he had asked for nude pictures was in fact the child's mother, pervert Greg Causton asked if he could sleep with the teenager anyway.
Prosecuting attorney David Thomas told Cardiff Crown Court that the woman, who cannot be named for legal reasons, was initially warned by her older teenage daughter that Greg Causton, 28, had been sending her sexual messages over Facebook.
The alarmed mum sprang into action, setting up a profile in the name of her younger teenage daughter and adding Causton as a friend on the site. When Causton - who claimed to be 20 - asked her how old she was, the woman gave her younger daughter's age.
The court heard that several exchanges followed between Causton and the woman, whom he believed to be a girl under the age of 16, with his messages quickly becoming sexual in tone. At one point, he even asked the 'girl' to send him pictures of her breasts.
It was at this point that the mother of the two girls revealed her true identity. But instead of fleeing in fear or apologising for his lewd behaviour, Causton responded to the revelation by asking the woman for permission to have sex with her daughter.
She immediately contacted the police, who arrested Causton and charged him with attempting to cause or incite a child to engage in sexual activity.
The South Wales Argus reports that Marian Lewis, defending, told the court that Causton made the sexual overtures through 'boredom' and 'the influence of cannabis'. She said that her client had shown genuine remorse over his conduct.
"When she said her age you didn't stop," presiding judge Richard Twonlow observed. "Your response, remarkably, was to ask if you could have sex with her daughter."
Judge Twonlow sentenced Causton, of Newport, to two years' imprisonment and barred him from working with children.