After decades in the making, the heavily-reported court case between the family of mining magnate Peter Wright and Gina Rinehart might might be turned on its head by an almost 40-year-old letter from Lang Hancock to his daughter.

During the document-swapping requirements prior to the case, the letter was uncovered as part of the action between Rinehart and her own son, John Hancock.

Press PLAY to hear the latest in Australia’s biggest mining court case

Nine News reporter Jesinta Burton told Gary Adshead on 6PR Mornings the court case will now likely focus on a cycle of exper witness testimony.

“Whether we’ll see Australia’s richest woman on the stand is yet to be seen.”

Image: Getty Images/Matt King/Susan Debra Windmiller