The Australian Story episode Into the Lion's Den showcases some rare, colour footage of Special Operations Australia commandos training in secret during World War II.

Shot in the remote bush of Fraser Island in Queensland, well away from the public gaze, it is a glimpse into the world of espionage and the art of killing as taught more than 70 years ago.

The commandos were being trained for operations behind the Japanese lines throughout South-East Asia.

The vision shows the men learning how to use weapons, setting limpet mines to blow up shipping, practising bush survival skills and fighting in unarmed combat. It is entertaining, yet chilling.

A Z Special Unit commando learning how to set a limpet mine to blow up shipping. ( ABC News )

The footage came to light when director Graham Shirley was recording interviews for the Defence Department with members of Special Operations Australia (commonly referred to as Z Special Unit) veterans, many of whom have since died.

"I didn't know the footage existed ... and then a couple of the guys I was talking to mentioned they'd been filmed in passing," Mr Shirley said.

Mr Shirley tracked down a can of Kodachrome 16mm film at the Army training headquarters in Sydney and found a tantalising treasure trove documenting the beginnings of Australia's first commando force.

"I thought it was a wonderful find and it ticks so many boxes: it's well shot, the colour's well preserved, it's an evocative glimpse of the World War II era," he said.

"I thought it was superb. What really brings World War II to life is colour.

"The Americans filmed the war in colour — look at The Battle of Midway — but it was expensive and most of Australia's war correspondents worked in black and white."

Cameraman only person invited to film Z Special Unit

A note on the box indicated the cameraman was a Dr Frank Tate.

Inquiries made by Australian Story discovered Dr Tate was a medical student working in Egypt during World War I.

By the time he came back to Melbourne to work as a GP, he had become an enthusiastic amateur photographer, setting up a theatre in his back garden to show his family movies.

He went on to film the Great Barrier Reef in colour during the 1930s — "a notable film, hailed the world over" remembers a relative, Geoff Tate — and won many awards for his photos.

Dr Tate also worked with Walt Disney and invented an animation device in his garage workshop.

He was also a friend of Australian filmmaker Frank Hurley, who had famously documented the ill-fated Shackleton expedition to the Antarctic in 1914.

By the 1940s, Dr Tate was an accredited army photographer, filming in New Guinea and as far as history records, the only person invited to document the activities of the so-called Z Special Unit.

His son Peter Tate, who inherited much of his father's slides and film, remembers seeing off cuts of the Fraser Island footage as a child.

"There were a lot of naked guys running around a wrecked ship and fellows pretending to knife each other," Mr Tate said.

He recalls his father "going off to the camp and coming back with a lot of sample weapons".

Dr Tate died in 1977. Much of his work is held by the National Film and Sound Archive in Canberra.