A woman who successfully fought a seven-year legal battle to prove she was the daughter of the former king of Belgium, Albert II, will learn next month whether, against the wishes of her father, she will be able to use the titles Her Royal Highness and the Princess of Belgium. Delphine Boël, 52, an artist and sculptor, whose mother had an extra-marital affair with Albert in the 1960s and 70s, argued in the Brussels court of appeal that she should also be able to use her biological father’s surname of Saxe-Coburg. The court will give its judgment on 29 October. King Albert, 86, who abdicated from the Belgian throne in 2013, was forced to acknowledge he was Boël’s biological father after a court-ordered DNA test last January. Boël, who had spent time with Albert as a child, nicknaming him Papillon (butterfly), had sought acknowledgement more than 20 years ago but her requests had been rejected. She launched a legal battle to prove paternity in June 2013, after the elder of her two children, Joséphine, was admitted to hospital with pneumonia, and she felt the absence of her biological father. Boël’s claim received a vital boost last autumn when the court of appeal ruled that Jacques Boël, with whom she grew up, was not her biological father and instructed an expert to carry out a test to compare her DNA with Albert’s. The king agreed to provide a saliva sample – which proved his paternity – after the courts threatened to fine him €5,000 (£4,370) for every day he refused. Marc Uyttendaele, Boël’s lawyer, said she simply wanted to be treated the same as Albert’s other children. “Those titles are things that belong to her, just as they belong to the other children of King Albert. My client never had any other intention than to be treated in exactly the same way as the other children of the king, her brothers and sister,” he said. Alain Berenboom, who is acting for the former king, said the issue of royal titles should be in the hands of the state, rather than the courts. “As far as the title is concerned, it is not a prerogative of the court but a prerogative of the executive power, in our opinion”, he said. On the day Albert stepped down from the throne seven years ago, citing ill-health, Boël’s mother, Baroness Sybille de Selys Longchamps, gave a TV interview where she spoke publicly for the first time about her affair with the king. “I thought I could not have children because I had had an infection,” she said of the relationship, which is said to have lasted from 1966 to 1984. “We had not taken any precautions.” She continued: “It was a beautiful period. Delphine was a love child. Albert was not the father figure but he was very sweet to her.”