Today, the court was told Symonds, an officer decorated for bravery in the aftermath of a gunman's shooting of three fellow senior constables in Napier nine years ago, accepted a written apology from Walker, whom he had known for about 10 years.
Judge Arthur Tompkins reckoned Walker barely deserved the officer's indulgence.
The judge said the apology, in one of separate letters to the victims, came too late for any special consideration in minimising the sentence.
Walker had also pleaded guilty only after a sentencing indication hearing which was held last month, more than six months after the attack.
Walker was already in prison after being sentenced on burglary and other charges moments before the attack last Christmas.
Outlining the assault, Judge Hopkins said Walker became angry with the sentence, as it was worse than he had expected.
To placate him, the officers agreed to get him something to eat but when they returned to the holding cell where he had been brooding, Walker used his foot to block them getting out and started the attack with punches and kicks.
The judge highlighted the aggravating factors, particularly the impact on two officers who were treating Walker "perhaps" far better than he had deserved.