She had suffered the injury in a fall in the kitchen of her home in Calverley, Leeds, on November 11 2002.

The much-loved wife, mother and grandmother had until then remained reasonably active, enjoying time pottering about in the garden with her husband John after retiring from the family shop.

He was a smallholder and dairyman when she married him but after the sale of his farm and milk rounds they took over her parents' grocery/butcher shop in Calverley.

After their retirement, they bought a touring caravan and spent several weeks at a time travelling the country until Mr Hall had a heart attack after which they stayed more at home and turned to gardening as their main hobby.

But she too was getting more frail. She was registered blind, wore a hearing aid, suffered from arthritis and was becoming quite forgetful – a doctor at Leeds General Infirmary described her as "pleasantly confused".

In her confusion, she sometimes pulled out medical devices or threw blankets onto the floor on ward 36 at the infirmary where nurse Colin Norris was working the night shift in the early hours of November 20.

About midnight that night he predicted her collapse. Several hours later he gave her the opiate diamorphine to make her drowsy before administering a fatal overdose of insulin.

Hospital staff were puzzled about her collapse because she was not diabetic and made desperate efforts to revive her over several hours. Norris was among those involved, although one doctor said he became "annoyed" that the nurse was slow to react.

Her son Stuart received a call at 5.30am telling him his mother had taken a turn for the worse and he rushed with his father to her bedside where they were warned there was little prospect of her recovery. "Nursing staff were rushing around. It seemed slightly chaotic but it was organised, machines and equipment everywhere," he said.

Pinprick blood tests were being carried out on his mother's fingers to get blood readings every few minutes. "They eventually ran out of places to prick the finger."

She was moved to another ward but her condition did not improve and she began having seizures.

In the meantime, blood tests revealed beyond doubt that she had been injected with a massive overdose of insulin.

A fortnight later they were told police had been called in. She died on December 11.

"It was a shock to find she had taken a turn for the worse and another shock to be told the police had been called in but at the time we just thought if somebody's made a mistake with her medication then mistakes happen," said Stuart Hall.

"But then the police found out it wasn't just a mistake, it was a murder inquiry, and that was just another shock."

He had even taken a box of biscuits to the nursing staff on Ward 36 after his mother's collapse as a thank you present for their work.

Of Norris, he said: "I don 't understand his motive and we are not going to get an answer.

"I think after five years the anger has calmed down. The main thing is that we now know he has got the knowledge to kill people and to do it discreetly.

"That makes him a danger to society and he must be kept inside."

Family and friends had noticed she was getting slightly more frail and forgetful in previous months but until then she had remained active.

Her only son John had even joked with her at her 90th birthday a few months earlier that she would get a 100th birthday telegram from the Queen.

She was taken to ward 36 at Leeds General Infirmary and it was here she became nurse Colin Norris's first victim. She survived a huge overdose of insulin but remained very ill and died the following January.

Mr Wilby said it was several months later when police contacted him to say they were investigating her collapse.

He was now convinced something untoward had happened to his mother and the other patients.

He had hoped she would come to live with his family at their Oxfordshire home as she became more frail but her collapse blighted her final months. She needed intensive nursing and had never really recovered her faculties.

"It's that kind of thing which makes me, not angry, but sad. It's very difficult to come to terms with," he said.

"As a result of someone's actions her last few months were taken away from her.

"The difficult thing looking back is that we had my mother's funeral and you start grieving and you come to terms with it but because we've had the trial hanging over us since 2003, we've not been able to do that properly."

Born in Kirkstall, Leeds, two weeks before the sinking of the Titanic, Mrs Wilby married her husband Norman in 1943 at Burley Methodist Church after they had met at Price Tailors in Kirkstall, which later became United Drapers and John Colliers. Son John was born the following year.

She worked as a secretary there and and later at Leeds City Council and the probation service. She retired in 1975.

She lived in Rawdon for 60 years. Her husband was a Labour councillor for 30 years, at one time chairman of Aireborough Urban District Council.

"He was chairman in Coronation Year which meant they had to go round unveiling a lot of plaques and official duties like that," said Mr Wilby.

They were a close couple and his sudden death in 1988 hit her hard but she joined a bereavement group in Ilkley, a book club and was a member of the Humanist Society.

She liked to travel by bus for coffee at Bettys in Ilkley or go shopping in Leeds. Her family took her for trips to Bolton Abbey, where she enjoyed walking in the woods, or Harrogate.

She had recovered from a heart attack in 1993 and continued to live at home. She was becoming more forgetful and had taken to keeping a daily diary in case something slipped her mind.

Her son found her somewhat confused and frightened after surgery at the infirmary and noted there appeared to be a shortage of staff on the ward – several times she fell out of bed and when she pressed an alarm to go to the toilet it went unanswered. "We were concerned and I think at the time a bit angry at one or two of the things that happened to mum in hospital about her general care," he said.

Perhaps these extra demands were the reason Norris attacked her. Her son, who gave evidence in his trial, found him offhand and unhelpful.

"His whole attitude was to just turn his back and walk away when I was speaking to him. I misunderstood when he was talking about her going to Chapel Allerton thinking this was a nursing home which she would not want, rather than another hospital where she could recuperate, but he didn't bother to explain."

On the night of May 17, Norris gave her the powerful painkiller morphine – even though she had not complained of pain. She became drowsy and shortly before his nightshift ended he gave her a huge overdose of insulin.

Ninety minutes later she was found semi-conscious, suffering a sudden hypoglycaemic attack.

She did go to Chapel Allerton Hospital where her family found staff much more helpful.

Later she went to live in a nursing home in Ilkley before dying at Airedale Hospital, near Keighley, on January 30 2003 from an infection. Her son said: "I can look back on my father's life, what he achieved and what kind of man he was, with very pleasant memories and a feeling of pride, but with my mother, who was an equally decent person, it's been very difficult to start to think of her in those sort of terms – I can't get beyond the last few months of her life.

"She went downhill from being a woman who was starting to become forgetful but was
still fairly mobile and living with a reasonable amount of dignity to not being able to move.

"It feels as if I never really laid her to rest.

"The distressing part is that she could have died in peace; she could have had two or three more years or gone on to 100."

More on this story:

Nurse who hated old killed four women in hospital

Public inquiry must be held says son of Norris victim

I can't grieve properly for mother

She was convinced she wouldn't leave alive

Patient collapsed... just as the accused predicted

Hatred of elderly turned carer into new Shipman

Did another rogue nurse inspire plot to steal fatal drugs?