The victim, Bradley Kneebone, was also at the event with friends and had been consuming alcohol throughout that day.
He had been annoying various people throughout that afternoon by his intoxicated behaviour.
About 7.30pm, Hammond was introduced to him while the former was preparing to leave, having consumed a couple of alcoholic drinks.
Hammond became annoyed by Kneebone's behaviour and invited him outside to sort it out.
Kneebone agreed and both went outside when Hammond asked: "Do you want a go mate".
Kneebone attempted to diffuse the situation, put both of his hands out in front and gestured to him that he didn't want to engage in a physical confrontation.
Hammond threw a punch that struck Kneebone in the head, causing him to fall to the ground and hit his head on a wooden pole.
He was unconscious for a few minutes and suffered a fractured skull.
In explanation, Hammond told police: "He went to head-butt me and I gave him one punch and didn't hit him very hard as I knew he was drunk."
