Mr Stanhope, who was the Labor chief minister from 2001 to 2011, is ever reflective, especially as he approaches his milestone birthday.

"My father died at the age of 70 and I remember him talking about this notion of three score years and 10 being the span of a life," he said.

"It is an age when things go a little bit wrong, a bit skew-wiff [health-wise]."

Mr Stanhope is still looking fit, gardening, walking, bike riding and even bench-pressing 100 kilos.

He spoke of his pride in his achievements while in government (from the arboretum to decriminalising abortion), his regrets (the jail) and his decision to probably retire as a senior advisor to the Winnunga Nimmityjah Aboriginal Health and Community Services, based in Narrabundah, at the end of this year.

When asked if he would make a return to politics, he is adamant never, but then...

"When I see the president of the United States is 78 and the outgoing president of the United States is 74, I think, 'Oh geez'," he said.

"I have to say, it has crossed my mind if Labor and the Greens don't lift their game in the next few years...."

So it's possible?

"Nah, nah, nah," he said, over coffee at his favourite Narrabundah cafe.

Mr Stanhope has also spoken about the heart-pumping moment he discovered he did not have eight siblings, but nine.

He and his family discovered half-sister Maureen, affectionately known as "Mo", only a couple of years ago through her son in England contacting the Stanhope family in Australia.

Mr Stanhope's parents were both both English and the family migrated to Australia in 1950. Mr Stanhope was born the next year, in Gundagai.

Maureen, who is 76-years-old and lives outside Oxford, was the result of a relationship Mr Stanhope's mother had with an Irish soldier when his father was away from England, serving during World War Two. A permanent member of the Air Force before the war, Mr Stanhope's father spent the last two years of the war in Italy. Maureen was born in 1945.

Maureen was given up for adoption and Mr Stanhope's mother kept her a secret from the rest of the family. Maureen's son tracked down the family by scouring all the post-war ship registers, looking for Stanhopes. Maureen's adoptive family knew her birth mother had migrated to Australia and her name was on Maureen's birth certificate.

Mr Stanhope always thought he was one of nine children. Now he proudly says he is one of 10.

"Immediately I learned of her existence, I made contact and rushed over to England," he said.

"It was very emotional [meeting her]. My deepest emotion was for the pain I know my mother suffered for the rest of her life from the day she gave birth to Mo. I knew growing up my mother had a deep sadness and I never knew understood it until I met Mo. It's a lovely addition to the family."

His mother was late in life diagnosed with Alzheimer's and had spoken of another daughter.

"We had an inkling but no understanding of this other daughter," Mr Stanhope said.

"So when my nephew rang my brother and said, 'I think you're my uncle', the penny dropped and some of the oblique comments my mother made when she was suffering dementia suddenly made sense."

Mo is the second of the 10 children and Mr Stanhope is sixth.

Mr Stanhope wished his mother, who died 15 years ago, could have met Maureen again and realised the baby she gave up had enjoyed a very happy, fulfilling life.

"When I do talk to my mother [in my head], I tell her 'Everything's OK'. She can relax. Mo's happy," he said.

Mr Stanhope is looking forward to retirement with his wife Robyn, spending more time with their four children and 11 grandchildren.

But he may never retreat from public life, deeply concerned for the wellbeing of the underprivileged in Canberra. He is spending two days a week advising Winnunga Nimmityha Aboriginal health services CEO Julie Tongs. He wants to retire this year but even that is not certain, saying the role he has held for the last five years has been a privilege.

"There is so much unmet need in the Aboriginal community, so much disadvantage," he said.

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