Lynda La Plante made this film after watching reality-TV crime shows. After calling Scotland Yard and learning that there were only four female DCIs, she interviewed one of them (Jackie Malton), who impressed her so much that La Plante decided to base the plot on Malton's experiences during her career.
According to Lynda La Plante, on the documentary about the making of Prime Suspect (1991), when she called the Metropolitan Police (aka 'Scotland Yard') and enquired as to how many female DCI's there were on the force, the woman who answered her call said, "Oh, quite a number! Four!" Jackie Malton appears on the same documentary, noting that she was one of three DCI's on the force at that particular time.
On the documentary following the second half of Prime Suspect 7: The Final Act (2006), Helen Mirren notes that Jackie Malton and her colleagues gave the first "Prime Suspect" a standing ovation because they felt it was the first time the police had been accurately portrayed on television.