Hundreds will gather at the historic Port Arthur site on Thursday to mark the anniversary of the 1996 massacre.

Prime Minister Malcolm Turnbull has flown in for the service, and John Howard will also be present. 

Ms Thompson, who lost her father, has chosen not to attend.

“It’s been 20 years, why relive that day again?” she said.

“I’d rather come together as a family to celebrate my father’s life.

“Dad wouldn’t want us to relive that trauma.”

Royce Thompson was a bus driver who had driven tourists to Port Arthur on April 28 like he did every Sunday.

He and two other bus drivers were approaching the Broad Arrow Café after hearing gun fire when Martin Bryant exited it armed with a rifle.  

Mr Thompson turned and fled attempting to get to the back of the bus for cover, but was fatally shot.

Royce’s wife, Colleen, won’t attend the commemoration either.

She’s chosen to go for her weekly game of golf.

Ms Thompson was 20 when her father was killed, and she still remembers the police delivering the death knock to her family home.

“I felt so much fear when it happened, like [Bryant] was going to come and get me,” she said.

Mr Thompson was a truckie turned coach driver who had worked hard all his life to provide for his family and set himself up for retirement. 

He had a warmth about him and an infectious smile, Ms Thompson said. 

Until this year, she had only visited the Port Arthur site twice in the 20 years since the massacre.

Travelling to Port Arthur from Hobart, just like her father would have, only reminded her of his last bus trip.

She returned to the Tasman Peninsula earlier this year with her two young girls.

“I saw it in a different light,” she said.

“I’d never felt the beauty of the Tasman Peninsula before, just feelings of pain and hopelessness on the drive down there.”

She explained to her girls what had happened to their grandfather.

“Taking the kids down there was really therapeutic,” she said.

“They didn’t understand, but I needed to tell them so they can grow with it.”

Ms Thompson has strong views on keeping Australia’s gun laws as tight as possible, and said the recently aired Sunday Night program opened old wounds and brought back fear.

The program played police interviews of Bryant, and depicted him giggling and denying his crimes.

“I used to feel a little bit sorry for him to some extent and I used to have a bit of forgiveness in me,” Ms Thompson said.

“Now that I’ve got kids, I don’t anymore.

“He wanted it to be remembered, but I don’t want to succumb to his wishes of notoriety.”