Andrew Cuss, of Woodford Court, Gloucester, was found guilty of three counts of indecent assault and one count of buggery after a jury trial.
Yesterday the 38-year-old appeared at Northampton Crown Court to be sentenced for the crimes.
Cuss was handed a nine year prison sentence by recorder Paul Bleasdale QC, though he will be eligible for parole after serving two thirds of the term.
Mr Bleasdale said: “I am satisfied you went about grooming (the victim) for sexual activities by encouraging him in activities he did not wish to participate in.
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“There was an element of coercion.”
The recorder also said that the victim had found the trial a ”very upsetting experience” and was finding the crimes “difficult to come to terms with”.
Mitigating for Cuss, Jane Rowley said the defendant had “limited intellectual function” and was an isolated man with no friends or family connections.
“He is not malicious, vindictive or evil,” she said. “He is a man who has tried to control his predilection but has had to acknowledge they are greater than he thought.”
Mrs Rowley added that Cuss’s crimes were committed out of “boredom and isolation” and said the defendant was willing to seek help during his time in prison.
Cuss, who was already signed on the Sex Offenders’ Register for previous offences involving downloading child pornography in 2010, will also be subject to an indefinite Sexual Prevention Order.