An apprentice electrician has been jailed for an unprovoked assault despite a police chief telling the court he was a "model son".
Darren Gilchrist, 23, from Alyth, Perthshire, was given five months for his part in an attack on Sean McGowan.
Tayside Police Ch Insp David Barclay, who is friends with Gilchrist's parents, described his behaviour as "out of character".
However a sheriff said he had no option but to jail him and his two co-accused.
William Mahoney, 22, and Gary Thomson, 23, were also found guilty of carrying out the Hogmanay attack after a trial.
Perth Sheriff Court heard that Mr McGowan was repeatedly punched and kicked on the face, head and body to his severe injury after an exchange of words in the street.
The assault, in Market Square, Alyth, during the early hours of New Year's Day 2009, left the victim needing a plate inserted in his jaw.
In a letter Ch Insp Barclay told the court he was a friend of Gilchrist's parents and had known him since a baby.
He said: "Since becoming a teenage Darren has always been a mannerly individual, always polite and respectful. I would describe him as comparatively shy and reserved in general terms.
"He was well brought up and had good qualities instilled in him by both parents."
He described Gilchrist as "hard-working, mild mannered and respectful" and said the incident had caused him to "carefully look at his choice of friends."
"I was shocked when I heard he had become involved in such a serious incident and can assure you this is out of character and not normal behaviour," he added.
"He is a genuine, nice polite young man, who - apart from this incident - has been a model son for his parents."
However, Sheriff Michael Fletcher said that because of the sustained and unprovoked nature of the assault he had no choice but to send all three to prison.
"It was an assault which was carried on for a significant length of time," he said.
"I do not think I can deal with it in any other way than by a custodial sentence."
He told Mahoney it had been clear from the evidence that he had aimed the kick which left Mr McGowan with the most serious injury to his jaw.
Mahoney of New Alyth, was jailed for nine months, while Gilchrist and Thomson, of Blairgowrie, were jailed for five months each.