It is one of New Zealand's oldest cold cases and today the Weekend Herald revealed police are now investigating his disappearance, almost 62 years later, because they received new information late last year.
Bennett, now 58, is heartened by news of the investigation.
She says her mother, Nell, only told her of Peter's existence when she was about 12.
"Mum had high blood pressure and used to hold her emotions in. She kept a lot to herself but she did share some thoughts about what had happened to Peter.
"I remember she hated peacocks and I never knew why until doing the Sensing Murder story when people talked of peacock feathers being found on the bed he was sleeping in at the farm. Apparently, people are superstitious about having them in a house as it's a sign of bad luck.
"I really hope we can get some closure, especially for Gavin. You just never know what might come out of all this now."
Gavin Boland told the Weekend Herald that it was beyond his "wildest dreams" that police were now investigating his brother's disappearance.
Police say they are determined to find out what happened to Peter, and have told the family they want to "put right" the apparent failure to investigate properly in 1957.
The boy, from Avondale in Auckland, was on holiday at a farm in the Waioeka Gorge and was reported missing by four men who were on the property when he disappeared. The men - three of whom are still alive and are now aged in their 80s - say Peter went missing on the morning of August 31, 1957, while looking for horses near the farmhouse. The four men are Ken (Kenneth) Woods, his brother-in-law Arthur Brasting and Peter Innes Smith. Les Smith, a friend of Arthur's, died in 2015.
"We intend to speak to the three surviving men who were at the farm at the time and who we understand are the only known witnesses to Peter's disappearance," officer in charge of the investigation, Detective Sergeant Rob Lemoto, said.
"The fact no trace of a healthy, intelligent, 9-year-old boy who had been taken to the farm with family friend Ken Woods was ever found, should have been cause for greater concern at the time," Lemoto said.
"No footwear, no clothes, apparently no footprints and definitely no body. That's very unusual, particularly given the stories the men reportedly told of the time Peter went missing - looking for horses in the morning, just a kilometre or so from the farm house." Gavin Boland still hopes for justice.
"I would like to find out what happened and, if it was an abduction or murder, I would like to see the person punished."
• Anyone with any information regarding Peter Boland's disappearance should call Bay of Plenty Police on 07 213 0328 or anonymously contact Crimestoppers on 0800 555 111.
