A retired accountant who knifed her husband to death had seemingly had a loving and contented relationship with him for more than 20 years, according to the couple’s friends and relatives.
Jackson admitted manslaughter, but denied murder, claiming she had suffered years of bullying and physical abuse from him.
During her trial at Bristol Crown Court the jury heard that the victim was the defendant’s fourth husband, and she was his third wife.
The early years of their relationship had been scarred by tragedy.
Jackson was married to her first husband at 18 and had two daughters with him before leaving after claiming he turned violent.
The court heard Jackson’s second husband had been gay, and that her third husband had taken his own life when he learned of her affair with the victim.
Jackson’s youngest daughter was fathered by her third husband, but was raised by the victim as his own from birth and later officially adopted by him.
The jury heard David Jackson had two daughters and a son from his first marriage, which ended when he began an affair with his second wife, Sheila Taylor.
The victim’s marriage to Ms Taylor would end when he began his affair with Jackson.
Ms Taylor said she had learned of the victim’s subsequent affair with the defendant when Jackson rang their home and demanded to speak to her husband.
She said the victim had been “white and shaking” when he came off the call, adding: “He told me he had been having an affair with a woman called Penny but the relationship was now over.
“(Jackson) didn’t want the relationship to be over and she was insisting he tell me about it and go and live with her.”
Shortly after Jackson and the victim married in 1996, David Jackson’s son Gavin took his own life.
Ms Taylor said Gavin Jackson, who was married to her niece, had killed himself after starting an affair while his wife was pregnant.
“He left a note saying he didn’t want to be like his father,” Ms Taylor said.
“Because, I believe, Gavin was having a relationship with another woman and he didn’t want to be like his father who had a relationship with another woman.”
The jury heard the defendant had worked in administration and accounts in the Royal Air Force and later the army, where she met the victim who had worked his way up from private to lieutenant colonel.
Before settling in Somerset, the couple had lived in Germany and France.
Their daughter Isabelle Potterton, 31, recalled three incidents of “serious aggression” by her father against her mother that occurred around 1997 or 1998 while they were living in Germany.
On one occasion the victim had forced Jackson against a wall and given her a bloody nose, and on another had pulled a knife on her, she said.
Mrs Potterton described a third occasion when her father got her out of bed, told her to get a mug she had got Jackson for Mother’s Day out of its hiding place and smashed it in front of her.
But she agreed the incidents had taken place shortly after Gavin Jackson’s death – an event which “broke” her father – and that he had sought counselling to deal with it.
Mrs Potterton agreed that her parents seemed to be enjoying a happy retirement together, and had lots of shared interests including a love of cruise holidays and gardening.
Prosecutor Christopher Quinlan QC said: “You’ve heard your unit, if I can put it like that, described as a very tight one – the three of you against the world. Do you agree?”
“Yes,” Mrs Potterton replied.
In recent years, the first sign something was wrong in the Jacksons’ marriage came on December 23 2020 when police were called to their address following a row over a TV remote control.
The defendant told officers she had locked her husband in their conservatory so he would “calm down” but that he had smashed his way out with the poker from their wood burning stove.
She claimed he had been acting out of character following an operation to replace the battery in a deep brain implant used to manage a condition that caused his hands and limbs to tremble.
Jackson even filmed the row, and the victim can be heard offering to leave her if she wants him to and walking away from the house.
The jury heard Jackson had filled out a police violence questionnaire saying she had not felt isolated, depressed or stalked.
When an officer telephoned her a few days later, Jackson said she and her husband had sorted out their problem and he had turned the voltage on his pacemaker battery down and was back to his normal self.
The prosecutor suggested that if she had been living in fear of the victim, Jackson would not have felt comfortable antagonising him by filming the row.
Police investigations later found that Jackson had made several online searches for terms including “deep brain stimulation”, “domestic violence”, “my rights as a victim”, “refuge”, “support with legal options”, “I’m living with my abuser” and for “divorce lawyers”.
Among a stream of WhatsApp messages she sent in one day in December 2018, she described him as having turned into the “devil incarnate”.