Robert Sherwood also had more than 2,500 indecent photos and videos of children as young as two on his laptop.

Sentencing at Nottingham Crown Court, Judge Jonathan Teare told the 29-year-old that he would stay behind bars until he was no longer a risk to the public.

Once his sordid secret was out, Sherwood ran off and sent panicky texts to his father, apologising for bringing disgrace on the family and suggesting he might take his own life.

One message told his dad where an encrypted computer was, and asked him to destroy it.

Sherwood, of Rutland Crescent, Harworth, walked up to a police car near Harworth Colliery that same night in February and handed himself in.

Dawn Pritchard, prosecuting last Friday, said Sherwood's victim was interviewed by police via videolink.

These charges 'opened the floodgates' to unearth the defendant's perverted online obsession.

He had 2,645 indecent images and videos, and more than 120 of these were the most serious classification.

But Harry Owen, defending, said: "Until 12 months ago, Mr Sherwood would have been amazed if he had been told he would be in the position he is today."

"Over the last year, his addiction to pornography has been growing at an alarming rate."

"Mr Sherwood clearly received some gratification on a number of occasions from this, but he was disgusted with himself in between."

Mr Owen said his client had no explanation for the sexual assaults, adding: "It's something he was responsible for, but cannot explain, and the psychological report goes along with that."

"When he was caught, he considered taking his own life, but was concerned he might cause harm to other people in the process."

Sherwood showed no emotion as his sentence was announced.

"Even experienced psychologists found it difficult to see how at your age, you suddenly lapsed into deviant sexual practices in the way that you did," said Judge Teare.

"You were depressed and upset about your job situation and turned to your computer for interests. You then started looking at adult pornography, and then child pornography."

He added: "You knew that child pornography is not a victimless crime, and the psychological impact on their future years will be great."

"Then you exploited your sexual deviance with a five-year-old boy, raping him four times and attempting one other."

"One simply cannot tell what the psychological impact will be on him in years to come. It has had a devastating effect on him."

"I am satisfied from the evidence of the psychological report, the pre-sentence report, and in my own assertions, that you represent a significant risk of causing further serious harm in future."

Sherwood was given an indefinite prison sentence for public safety.