Daniel Potts, 29, of Colchester was caught in a “classic undercover officer sting” as he sent twisted messages to a decoy.

Chelmsford Crown Court heard he sent her explicit pictures of himself and tried to “teach her to masturbate”.

Jerry Hayes, prosecuting, said: “The defendant made it very clear repeatedly that he wanted to meet with her and engage in sexual activity. He asked for a naked picture of her.”

Judge Walker said only a sentence of immediate imprisonment would do, adding the facts “clearly indicated” Potts had a sexual interest in children.

“Your incitement involved repeated communications with a child, who you thought was only 12 years of age,” he said.

“You sent various photographs and videos of yourself masturbating, thinking that a 12-year-old would be seeing those.”