Mr Robertson is co-owner of The Scottish Arms and he has always been fascinated by a poster on the hotel's wall of a soldier in Vietnam.

Distributed by the Australian Department of Veteran Affairs, the image showed a soldier holding a gun and was accompanied by the words "Salute to Vietnam Veterans".

Mr Robertson said he would often sit with a quiet beer and ponder about the man's identify.

"We were given a collection of photographs from the local Vietnam Veterans Association years ago," he said.

"We display them, but this one kept haunting me.

"It is such an iconic picture and he seemed to be looking at me, you know?

"This year I decided to track him down."

Mr Robertson began his search, but didn't hold much hope.

Surprisingly, it took a lot less work than anticipated. He contacted Australian War Memorial director Brendan Nelson, who he had previously met.

Mr Nelson provided the soldier's name, Sergeant Peter Buckney, along with a phone number.

"In two calls, I had him," Mr Robertson said.

"Within three days, I had all the information from Brendan in my mail box.

"He was extraordinary."

The two Peters found common ground during their phone discussion.

In fact, Mr Buckney has agreed to travel from his Victorian home for Bowral's Anzac Day commemorations.

Mr Buckney will attend the dawn service and will return to the Scottish Arms for lunch and Two-up in the afternoon.

"Any veterans are welcome to meet him," Mr Robertson said.

He said he was impressed by Mr Buckney's warm personality.

"Peter was great, I found him very professional and humble," Mr Robertson said.

"He doesn't want to make a fuss about his visit."

Mr Robertson said he had held a long-term interest in Vietnam veterans.

"I feel close to them because I'm from the same era," he said.

"I was young (at the time), but there is an attachment to my era."

Mr Robertson said his pursuit to solve the mystery had received praise from Mr Nelson, who told him that "I had made his day".

Through further research, Mr Robertson discovered the photo was taken by Peter Anthony Ward.

The photo was taken in South Vietnam in 1970-71 and Mr Ward wrote that the amount of weaponry Mr Buckney had carried was "typical of the load carried by Australian soldiers on operation".

"He is moving along a jungle path during Operation Atherton in Southern Long Khanh Province," Mr Ward wrote.

"Sgt Buckney's unit, D Company of 8th Battalion, The Royal Australian Regiment (8RAR), was conducting its first major operation since arriving in Vietnam in November 1969."