The programme was screened on the Vier channel on Tuesday night. A further episode is planned.
The programme makers had made an appointment with the baroness on 3 July exactly the day on which King Albert announced his abdication.
In his address to the people of Belgium the king does not mention Delphine. Baroness Sybille de Selys Longchamps: "There is something missing. It will have to be said some day."
The baroness then gets a call from her daughter: "It would have surprised me if he had said anything important" Delphine says.
Baroness Sybille de Selys Longchamps first met the then Prince Albert in Greece where her father was the ambassador: "From the start I felt that we were not indifferent to each other."
"Months later I was invited to a dinner. I was seated next to Albert. I immediately realised this was done on purpose."
"Paola was furious. She butted him with her elbow once or twice. At that point I realised he had feelings for me."
From then on the baroness and the prince saw each other every day. The affair did not reach the Belgian media, but abroad paparazzi tracked down the couple. King Boudewijn intervened to put pressure on the baroness's father to end the affair, but to her surprise the baroness became pregnant in 1967.
"I thought I could not have children because I had had an infection. We had not taken any precautions."
Delphine's mother remembers Prince Albert didn't think it was a catastrophe. He was in the neighbourhood when she had her baby and sent flowers.
She moves to Knokke where she lives separated from her husband. Albert is a regular visitor.
"It was a beautiful period. Delphine was a love child. Albert was not the father figure, but he was very sweet to her."