AN opera loosely based on the story of the missing Beaumont children has been described as outrageous and adding to the suffering of the family. The production is being developed by the State Opera of South Australia in partnership with SINGular Productions. It is planned to premiere in 2016 to coincide with the 50th anniversary of the disappearance of the Beaumonts, Jane, 9, Arnna, 7, and Grant, 4. They failed to return home on Australia Day 1966, after a trip to Adelaide's Glenelg beach. The case remains unsolved and has been subject to publicity for decades with a Dutch psychic called in at one stage to help solve the mystery. The opera will actually be based more directly on a novel by Adelaide writer Stephen Orr called Innocence Lost, which used the Beaumont's story as its inspiration. On Friday a man who said he was a friend of Jim Beaumont, the father of the missing children, expressed some anger over the planned production. He said Mr Beaumont, who was now in his 80s and suffering from the early stages of dementia, had "suffered incredibly every day" over the disappearance of his children. "Now to find that it's going to be in an opera is outrageous," Peter told ABC radio. At least wait until the man is dead. His suffering has been immense. State opera artistic director Timothy Sexton said the Beaumont's story was a "tragic case" and there had been other similar cases since then. "I think it's important to visit those and look at the intensity of these things so people can understand these issues better," he said.