His partially stripped body was found in the canal four days later. He had suffered 12 skull fractures. The hammer was found on the towpath.

Darren Colling...homicidal fantasies

His mother, Alice, 47, said her world "fell apart" when his battered body was discovered.

The court was told how after the brutal killing Colling, from Sale, Cheshire, picked up a Chinese takeaway and socialised with friends.

The next day he drove back to Cheshire, where he washed his bloody clothes and cleaned blood out of his car, but he later confessed the murder to his flat-mate and former lover Damien Sinclair.

Sentencing Colling, the judge Mr Justice Toulson said: "You murdered George in a planned attack of extreme brutality for sexual pleasure.

"You had anal intercourse with him when he was mortally wounded and threw him in the canal when he was unconscious, probably brain dead and gasping for air.

"It is obvious you present a risk to young men of the very highest degree."

He said: "No other young man and no other family must ever be put a risk to suffer from you in the way George and his family have suffered and continue to suffer and will suffer for years to come.

"I cannot envisage a time when you will cease to be a risk to young men, until you have reached a stage in life when all capability of sexual interest has ceased as a result of the ageing process.

"I shall be alarmed if anyone were to consider your release before then."

George, giving a piggyback to his younger brother Sam

Afterwards George's father, Barry Mortimer, 60, called Colling an "evil, devious and lying sexual pervert".

Mr Mortimer said: "His lies have no limits, he endeavoured to destroy the bonds that our family share with George in order to save his own freedom and continue with his depraved lifestyle.

'Sexual fantasies'

"Throughout the trial Colling falsely portrayed George as homosexual to give credibility to his defence and tried to assassinate our son's character."

He added: "He lured George and his brother Sam, 18, into the use of cannabis in pursuit of his own sexual fantasies.

"As a family we draw comfort from the fact other young boys will no longer be at risk from Colling."

Mr Sinclair, who gave evidence for the prosecution, told the court Colling had also confessed to fantasies of kidnapping, abusing and murdering young men.