Four members of a gang who attacked strangers at random, apparently filming some on mobile phones, have been jailed for the death of one of their victims.
All four defendants were convicted of manslaughter
A 16-year-old girl, Chelsea O'Mahoney, was among four people who kicked David Morley's head "like a football" on London's South Bank in October 2004.
Reece Sargeant, 21, Darren Case, 18, and David Blenman, 17, were sentenced to 12 years each for manslaughter.
O'Mahoney was given an eight-year custodial sentence.
The gang, from Kennington, south London, had been acquitted of murder.
Mr Morley was sitting on a bench with a friend on the South Bank when they were approached by the gang, who launched a sudden attack - smiling or laughing as they battered the pair, the court heard.
He died from multiple injuries later that night - his friend Alastair Whiteside still suffers from nightmares and insomnia.
Eight people were beaten and stamped on that night, in attacks carried out for pleasure, it was claimed.
In CCTV footage of the gang's last attack that night, on a homeless man who was kicked as he slept, O'Mahoney is seen holding a phone up, apparently filming the attack.
No pictures were recovered, but the judge, Brian Barker, Common Serjeant of London, said he had no doubt O'Mahoney was filming the assaults.
Sentencing the four, he said: "You sought enjoyment from humiliation and pleasure from the infliction of pain and you were clearly determined to continue and take advantage of any opportunity that presented itself.
CCTV pictures of one attack show O'Mahoney holding up a phone
"You called this `happy slapping' - no victim on the receiving end would dignify it with such a deceptive description."
Mr Morley, 37, from Chiswick, west London, was a gay barman who had survived the Soho nail bomb attack in 1999.
Det Insp Nick Scola said: "For him to lose his life in such a cowardly and pointless attack was a tragedy in every sense of the word," he said.
The gang was told they would each have to serve at least two-thirds of their sentences before being released on licence for the remainder of their terms.
The four were also convicted of conspiracy to cause grievous bodily harm.
Bar manager Mr Morley had survived the Soho nail bombing
O'Mahoney's lawyer said she was the child of heroin addicts, who had been found wandering the streets of London aged three or four and had had a "particularly chaotic and fragmented life".
The others were also described as immature and vulnerable to peer pressure - Sargeant was said to feel "deeply ashamed".
Mr Morley's father, Geoffrey, 76, said he was pleased the sentence reflected the seriousness of the offence but said he had seen little remorse from the defendants.
"Nothing will bring my son back," he said.
"At least it will be better for the public at large and perhaps better for them that they have a sentence that fits the crime."