The life of Princess Diana, in pictures, on her 60th birthday

The late Diana, Princess of Wales, was a trailblazer, a style icon and one of the most influential women of the 20th century.

But, by all accounts, once she stepped onto the stage of public life in 1980, self-preservation meant she lived in two separate worlds – one personality confidently in the spotlight as the adored People’s Princess, and the other as a more oppressed, scrutinised member of the royal family who struggled with insecurity and loneliness.

And never the twain shall meet.

As the thousands of newspaper articles shed light on her every move when she joined the royal household in 1981, books and essays revealed her inner turmoils and conflicts and documentaries spun various visual angles of her trajectory up to her death, possibly the most heartbreaking chapter of her life was just before she died.

She called her butler Paul Burrell in a marathon 40-minute phone call from her then boyfriend’s yacht the Jonikal floating in the Mediterranean. It was in the 24 hours before she was killed in the Pont de l’Alma tunnel in Paris. We only saw the paparazzi photos of her, looking slim and suntanned in designer one-piece swimsuits.

But in that candid chat she revealed so much more.

A recently completed ITV documentary, Diana, aims to tell “the definitive story of the most famous woman in the world” to mark what would have been her 60th birthday on July 1.

Executive producer David Glover says “her 60th birthday feels like the perfect time to re-examine her life and legacy and explore just how she went from a relatively unknown teenager to the most-mourned person who ever lived”.

However, there were possibly only a handful of people who could really lay claim to knowing the real princess behind closed doors.