Tony Dell was in his mid-60s, estranged from his wife and children and living in his mother’s garage when he realised his life had reached rock bottom.

For a man who had played Test cricket for his country and created a successful advertising business, it represented a dizzying and dramatic decline.

It took a chance meeting to lead Dell to a moment of discovery, and a remarkable journey on the path to helping himself and others.

His story is one rooted in sport and conflict but also the issue of mental health that continues to challenge society to this day.

Tony Dell is the only surviving Test cricketer to have seen action in a major theatre of war. He is also the only Test cricketer to have fought in the Vietnam war.

That he served Australia in combat and in cricket is even more peculiar because Tony Dell was officially still a “Pom” at the time, born and raised in Hampshire.

He was 15 when his family emigrated down under and he was dispatched to Vietnam after his number came up in Australia’s National Service lottery.

When he returned from a year-long tour of duty, he picked up where he had left off as a promising cricketer.

After a handful of first-class games, he was picked for an Ashes Test in February 1971 against the country of his birth.

“I felt like I had arrived,” Dell said.

Instead of the being the start of something though, it marked the beginning of the end.

His cricket and private life began to fail, a harrowing journey for him and especially his family.

It was that fluke meeting in his 60s, 40 years after coming home from Vietnam, that led to a diagnosis of post-traumatic stress disorder.

Suddenly all the pain and suffering, the anxiety and dysfunction, started to make sense.

He realised he had never confronted the horrors he had witnessed on the battlefield and, like so many before and since, had lived in silence with the awful consequences.

Dell has revealed to me the full traumatic story of his battle for a new book, And Bring The Darkness Home, published this week.

His resolve to do something for those who suffered like him led him on a journey.

His non-profit organisation Stand Tall for PTS has become a movement for greater awareness and support for military veterans, first responders and other victims.

Proceeds from sales of the book will support the charity’s work. Dell is hopeful of one day seeing a Test match designated as an event to raising awareness of mental health and PTSD.

Like so many veterans, Dell said, he had avoided talking about his time in combat. Even teammates such as the Australian cricket legend Greg Chappell had no idea he had ever been in Vietnam.

The cost to society is statistics like this: every day in the US, 22 military veterans take their own lives.

It is the overwhelming need for help that drives Dell on.

“The more I talk about it, the more that people see its not just them going through it, the more it can encourage them to talk, then I have done something worthwhile,” he says.

“It is my therapy. Let’s see what we can do to help others.”