A dangerous predatory paedophile with a strangulation fetish has been jailed for 12 years after using Facebook to groom teenagers into sexual activity online.

Robert Sinclair, 64, of Pine Hill, Epsom, described as a keen golfer and family man, was sentenced yesterday after pleading guilty to 33 offences described as “abhorrent” and “horrific” by the police.

In addition to sexual assault on a nine-year-old girl, Sinclair created multiple online identities that he used to trick youngsters into filming themselves on webcams naked or engaging in sex acts - including strangling themselves.

His victims came from across the country including six girls, aged from 12 to 14, and a 13-year-old boy.

Other offences that he was sentenced for at Guildford Crown Court included attempting to pervert the course of justice, blackmail, sending obscene communications and unauthorised use of a computer.

In January 2012, he approached a frightened nine-year-old girl in an alleyway in Epsom, stroked her under her chin and took photographs to feed his fetish for children's necks.

Prosecutor Christopher May said: "She appeared to be in an alleyway or street, looking frightened. In one of the images she was touched under the chin, her head being pushed back to expose her neck."

Mr May said a 13-year-old victim was groomed by one of his fake online personas, Max, who claimed that he was hospitalised due to a car crash.

He said: "The defendant had a particular interest in the neck and asphyxiation. He persuaded her into gagging and choking herself online so he was able to view the imagery."

Mr May said Max described a fantasy about nearly strangling her, adding: "She said she was asked to slap herself and force her fingers into her windpipe. She said she found it hard to breathe."

Through a website, he used another identity, Hunky Max, to offer to swap "gagging and asphyxia pictures of her naked" for similar original images.

The girl has suffered post-traumatic disorder, depression and suicidal thoughts as a result of his crimes between April 2012 and November 2013.

After his arrest in October 2013, Sinclair asked the teenager to delete incriminatory text messages and iMessages in an attempt to pervert the course of justice.

Indecent images of three other teenage victims were distributed through the same website between 2009 and 2013. Sinclair asked one of them for naked photographs on her return from abroad.

Mr May said: "He said he would send those he already had to her mother and sister if she did not comply to the blackmail demand."

Using one of his fake personas, Sinclair obtained naked images from two other 13-year-old girls.

He also sent naked images of a girl to a teenage boy to trick him. Mr May said: "He said he was promised a blow job if he showed his erect penis on the webcam."

In 2010 Sinclair accessed photos of a teenage girl from a computer without authorisation.

Officers from Surrey Police's Paedophile Online Investigation Team began an investigation following information about a profile which had been set up on a file sharing website to share indecent images of children which was traced to him.

He was arrested in October last year and answered no comment at interview.

Officers discovered that he kept a list of 398 email contacts including their ages, location and whether they had access to a webcam.

They also found that Sinclair had also downloaded child porn, showing a girl aged four or five, and possessed more than 100 indecent images and movie clips.

Enquiries are ongoing between Surrey Police and the National Crime Agency's Child Exploitation and Online Protection Centre to identify further potential victims.

Sentencing him, Judge Christopher Critchlow said it was "very sad" and "quite remarkable" that a married man of 40 years, with two grown-up daughters, would commit such crimes.

Sinclair was described as a good father, a sociable person and a keen golfer.

But Mr Critchlow said: "Behind closed doors you were doing all this. I'm sure you know the seriousness with which these offences are treated."

Defence lawyer Richard McConaghy said after having taken early retirement, Sinclair started creating false identities online.

Mr McConaghy said: "He has created a fantasy world, a fiction as far as they were concerned and a fiction as far as he was concerned."

He added: "What he lost perspective on was that there was a real world on the far side of what he was doing. It seems he became trapped in a dangerous spiral."

He said Sinclair had showed "remorse" and his family were standing by him. He said: "He is a man who has now woken up to the fact his behaviour was unacceptable."

The judge said Sinclair must serve half of the 12-year prison sentence and pay a £120 surcharge. An indefinite sexual offences prevention order was made.

Investigating Officer, Detective Constable Steve Branch from Surrey Police's Paedophile Online Investigation Team, said: "Robert Sinclair carried out an extremely organised and complex operation of horrific offending which has caused a huge amount of emotional trauma to the victims.

"He displayed abhorrent behaviour in targeting, grooming and controlling the children he struck up online relationships with.

"What he asked his victims to do was particularly unpleasant and dangerous. His actions could well be recognised by more victims not realising it to be Sinclair and we would encourage those people to come forward.

"Sharing indecent images over the internet is not a victimless crime and can have a lasting and repeated impact on those that are subjected to the abuse.

"It is a stark reminder that we should all remember to stay safe while using the internet and be on our guard against suspicious interaction from strangers.

"We will continue to relentlessly pursue those individuals who commit on-line offences and bring them before the courts, as we have successfully done on this occasion."

Anyone who has any concerns about having come into contact with Sinclair or anyone else of a suspicious nature should contact Surrey Police on 101 (999 in an emergency), or use the online reporting system found at www.surrey.police.uk.

Alternatively the independent charity Crimestoppers can be contacted anonymously on 0800 555 111.