Child molester Graham Capill deserved the brutal assault that left him bruised and whimpering outside Christchurch District Court, according to the former boxer who attacked him.

Daniel Andrew McNally, 28, an alcoholic sickness beneficiary, yesterday pleaded guilty to assaulting the former Christian Heritage leader after Capill's brief court appearance on a charge of indecency with a child.

The attack on Capill on March 23 was the latest in a long list of convictions McNally has gained since he first appeared in court at the age of 15. He was described as having problems with alcohol since he was 10.

Six years ago, Judge Murray Abbott said he had "an appalling record for violence" as he was being sentenced for a drunken attack on a female taxi driver, his seventh conviction for violence up to that point.

Since then, he has been dubbed "a complete nuisance" by Judge Edward Ryan in 2002 for another violent and drunken dispute with a stranger in a service station.

In October 2003, he was described as "a long-term drug and alcohol addict" by Judge Graham Noble who had "been provided with every opportunity - at taxpayers' expense - to overcome your difficulties".

"You begin but you never succeed and then to revert to form," Judge Noble said.

"Every sentencing option and every chance has been given to you but you're still assessed as a high risk of reoffending."

At that time, McNally was sentenced to 15 months in jail for stealing wine from all-night supermarkets, breaches of trespass orders banning him from going into supermarkets where he had offended previously, and pushing over a woman who tried to stop him getting away with money he snatched from the till.

In court yesterday, Sergeant Paul Brocas said McNally had learned the identity of Capill - then known only as a prominent New Zealander on child-sex charges with name suppression - because he had also been waiting in court to be called on.

"McNally, having heard the details of [Capill's] charge, became enraged. He left court and waited outside for [Capill] to leave," Brocas said.

"He followed him and ... lashed out with both fists. An associate wrestled McNally away and held him until police arrived.

"McNally accepted the facts and said he deserved it."

Rupert Glover (defending) did not seek bail.

Judge Stephen Erber remanded McNally for sentence this month and called for a victim impact report.