Mrs Martin had asked to speak to her daughter, Ben's mother, but she wasn't home. A few seconds later the phone line cut out.

Despite what she said, everything was far from OK at Mrs Martin's home in Humevale. The deadliest of the Black Saturday bushfires was almost certainly raging on the 16-hectare horse property known as Pine Ridge Stud where Mrs Martin lived with her husband Lloyd. The elderly couple's large brick home may have been on fire at the time of the telephone call. A fire investigator said the house may have been losing its roof.

Counsel assisting the Bushfires Royal Commission Peter Rozen said that the poignant telephone call was the last known contact anyone had with Mrs or Mr Martin.

The commission heard that on numerous occasions before Black Saturday and on the day itself, Mrs Martin said she did not want to stay on the property if it was threatened by fire. She told her daughter that no house was worth ''dying over'' and that they would leave and not be ''bloody stupid''.

The fit grandmother, who regularly played golf with her 83-year-old husband, told a neighbour the evening before Black Saturday that she intended to leave if the property was at risk from bushfire. But she added that she would ''have to convince Lloyd'' to leave.

The remains of Mr and Mrs Martin, who had been together since Mary was a 17-year-old theatre usher, were found in the collapsed house by police the day after Black Saturday.

The commission heard that the Martins were fit and robust, aware of the risk of bushfire and had taken extensive fire precautions. Mr Martin attended CFA information nights and the couple had a fire plan, fire hoses, a sprinkler system, pumps to pump water from the dam and a generator to provide power.

Police fire investigator John Kelleher examined the scene as part of the police investigation into the deaths.

In his report he said most of the brick veneer had collapsed and a large part of the roof was ripped off the house and was found about 30 metres away.

''Loss of the roof meant that the occupants were trapped in a house fire, unable to escape because of the bushfire,'' he said.