She mightn’t have realised it at the time but when Diana Nelson visited her dad in the Blue Mountains at the height of World War II she was at the heart of Australia’s secret chemical warfare industry.

“We all got in the car and trooped up there (one weekend),” she said. “(Dad) had a chef who’d been a chef at Romano’s which was a very upmarket restaurant in those days. We had beautiful little savouries . . . It was all very dainty, not what you’d expect to find in a (military) camp.”

But behind the fine dining, Diana’s father, Flight Lieutenant Wilf Myers, was in charge of a project that was stockpiling vast amounts of mustard gas in preparation for a possible Japanese attack. Like the rest of the country, the true nature of her father’s job in a series of disused railway tunnels at Glenbrook was a complete secret to the then 13-year-old Mosman girl.

“I wasn’t the sort of person to pry much when I was a child,” said Diana, who has lived at Wentworth Falls for the past 19 years.

Although his work was top secret, there were still hints of his dangerous war-time task.

“He was sick at one stage and I was told he had shingles, but obviously he got burnt (from the gas). I learnt that at a later stage,” said Diana.

The unacknowledged task of the Glenbrook armourers gained recognition in recent years following the publication of a book on Australia’s chemical warfare history and a History Channel documentary on the tunnels.

These events prompted Diana to look more closely at her father’s wartime role. Although he talked about it to family members when he was alive, he remained tightlipped whenever the contentious subject reached the broader public domain.

“He just said to me, ‘don’t you mention it to anybody. I don’t want journalists on my front door step’,” said Diana.

For a topic that remained a family secret for so long, the public interest in the Glenbrook tunnels has come as something as a shock to the Blue Mountains local, just as it has to her own grandchildren.

“They’re absolutely thrilled to think I have all this stuff and that something is being said about it now. They’re very excited about it,” she said.

Despite living in the Blue Mountains for almost two decades, Diana has never been to the Glenbrook tunnels where her father risked his life during World War II.

“I suppose I should go and look at the tunnels,” she said.