When Dickson, who was also Holden's neighbour, investigated the gunshots she saw smoke billowing from Holden's house.
Another resident who had also gone out to investigate the source of the commotion, Chris Cole, was nearby.
Gray appeared and began firing at the pair, shooting Cole in his lower back.
Unable to flee because of her age, two artificial hips and restricted movement because of surgery on her arm, Dickson helped seriously wounded Cole to the roadside, where they both collapsed.
When she noticed how badly Cole was hurt Dickson crawled on her stomach about 100m to a telephone booth.
After calling police and an ambulance, she crawled back to the wounded man and comforted him while they waited for help to arrive.
When she became concerned at the length of time it was taking for paramedics to get there, she crawled back to her house and called emergency services again.
She continued to update police as the night of terror unfolded, unaware that Gray had killed her son James.
Police eventually rescued Dickson and Cole, but Cole later died from his wounds.
Then-Governor General Dame Catherine Tizard, Prime Minister Jim Bolger, assistant Police Commissioner Peter Wiersma and Police Commissioner John Jamieson all praised Dickson for her actions that day.
Two members of the Invercargill Armed Offenders Squad (AOS) who had been called to Aramoana on the day of the shooting, Senior Constable Steve Dalton and Sergeant A.J. Harris, were among several police officers who went to Dickson's home to check on her after the gunman had been caught.
She invited them inside for a cold drink and they lined all their rifles up along her deck and relaxed there for a while.
Dickson died in 2007.
Her son, Lindsay Dickson, gave his mother's medal to the New Zealand Police Museum in Porirua last year, before borrowing it again for a family reunion so her many relatives and descendants could take pictures with it as they recounted stories of the courageous pensioner.
Last Friday Lindsay Dickson returned his mother's medal to the museum. Dalton and Harris were there when he arrived and the trio shared stories of the resourceful and brave woman they knew.
The police officers described Dickson as delightful and tough. She took great comfort from the friendly AOS members from Invercargill and she always referred to them as her "Invercargill Johnnies".