A man who kicked a father-of-six outside the Wonderland music festival has been found not guilty of unlawfully causing grievous bodily harm.

Jamie David Foster struck festival site manager Aaron Gill during a scuffle between staff and fence jumpers outside the Langley Park event in December 2015.

Mr Foster argued he had no choice but to kick out at Mr Gill, saying the older man was acting “over-the-top aggressive” and left him fearing for his safety.

Camera Icon Jamie Foster told the court he had ‘no choice’ but to kick out at the manager. Credit: Facebook

After a six-day District Court trial, a jury accepted the 20-year-old’s version of events and acquitted him of the charge on Tuesday.

Mr Foster was standing near a group of teenagers who were trying to pull down a perimeter fence during the final hour of the festival when Mr Gill rushed over.

Mr Gill was felled by a punch and was crouched down on all fours when he was hit to the face.

Camera Icon Jamie David Foster leaves the District Court. Credit: Danella Bevis/The West Australian

The blow fractured his forehead, nose and eye sockets.

Mr Gill was discharged from hospital the next day and had surgery to insert metal plates into his head once his swelling had gone down.

In his opening address, defence lawyer Philip Urquhart said Mr Gill overreacted and threw the first punch after Mr Foster told him to settle down and called him a derogatory name.

Camera Icon Mr Gill’s facial injuries.

He said his client was trying to kick Mr Gill’s arm out when the site manager was on his hands and knees, but he was grabbed by another person at the same time.

Mr Foster later told the jury he was not sure where his foot landed but said it may well have connected with Mr Gill’s face.

He said felt he had no other option but to kick Mr Gill to protect himself, and denied taking a run up, aiming for his head or using full force.

Camera Icon Aaron Gill leaves the District Court. Credit: Danella Bevis/The West Australian

“At the time I felt I had no other option… I wish the outcome was different but at the time I feared for my safety,” Mr Foster said.

Mr Foster had earlier jumped a fence to get into the festival but was quickly evicted by a security guard who he says was heavy handed.

He claims a group of security staff surrounded him after he kicked Mr Gill then took him inside and assaulted him to the extent he had to go to hospital when he was released from police custody.

Mr Gill admitted pushing one of the teens and throwing a punch during the fight, but he said he was not sure if it connected with anyone.

Camera Icon Aaron Gill leaves the District Court. Credit: Danella Bevis/The West Australian

Giving evidence last week, he described hearing a “massive crack” when Mr Foster’s foot connected with his face.

“The moment of impact there was a crack and then everything went white and I couldn’t see or hear anything,” he said.

“There was a tremendous amount of blood coming from my face.”