Widow shocked over husband's 'avoidable' death
Barbara Vavalidis had been planning a carefree retirement after decades of hard work and a busy family life.
Instead she is mourning the loss of her partner of 45 years, the father of her two sons.
Stefanos Vavalidis died in London in January 2016, aged 69.
He had fallen ill while on holiday abroad in May 2015, and spent the last eight months of his life in hospital.
His widow is suing Dr Peter Wheeler, a private GP who was the family's trusted doctor for more than 30 years, alleging he was poisoned through negligence.
Mrs Vavalidis's lawyer from Leigh Day solicitors said it was one of the worst cases he had known in more than 30 years.
Dr Wheeler was the doctor of Diana, Princess of Wales, and was the man who identified her body after she died in a car crash 20 years ago.
In his defence to Mrs Vavalidis's civil claim, due to be heard at the High Court next year, Dr Wheeler has admitted he was in breach of his duty by failing to properly monitor his patient by arranging the full blood tests, recommended in the standard medicines reference book for all doctors.
BBC News has established that Dr Wheeler is under investigation by the General Medical Council (GMC), which regulates the UK's doctors.
And the Metropolitan Police has confirmed it is looking into a complaint received about the case.
Dr Wheeler continues to practise medicine at Sloane Street Surgery in west London without any conditions.
An inquest last November found Mr Vavalidis died from liver failure and this was "most probably associated with toxicity" from methotrexate, a drug prescribed for his psoriasis.
'Poisoned drip by drip'
Mrs Vavalidis, 66, told me: "My husband took methotrexate once a week without fail. But he suffered an almost insidious build-up of health problems like colds and poor sleep.
"That was the nature of being poisoned - drip by drip by drip - over this very long period.
"It's heartbreaking enough to lose your partner of 45 years - but a complete shock and horror when we found it had been totally avoidable.
"We would caution people to think carefully about their choices of medical care and who is giving it to them."
The family had to have Mr Vavalidis flown back by air ambulance from Greece to University College London Hospital in July 2015. They have praised his NHS care.
Mrs Vavalidis added: "He was a very intelligent person and had been a great reader.
"But by that time it was clear his brain function had slowed considerably."
She and her elder son Alex accused Dr Wheeler of "arrogance, prolonged carelessness and negligence".
Alex, 32, said: "The duty of a doctor is to protect patients from harm. That's not what we got.
"It begs the question of whether the regulators are doing their job. This was not just a one-off - it happened over a considerable period of time.
"That last period of his life was horrifying. We'd like to prevent this happening to other people."
The Medical Defence Union, which is representing Dr Wheeler, said he was unable to comment "due to his duty of patient confidentiality and the ongoing legal proceedings".
Mr Vavalidis was first prescribed the drug by another doctor in 1999 and in 2003 Dr Wheeler took over prescribing it from him.
Breach of duty
Dr Wheeler states that Mr Vavalidis, who was obese and diabetic, would still have died of liver failure.
But Dr Wheeler admits that if the full tests had been carried out, his patient could have lived up to two years longer.
The papers also acknowledge that Dr Wheeler and the surgery did not have any system for flagging up the need for these regular tests.
His defence states that Mr Vavalidis, who was a successful banker, had wanted to reduce the number of clinicians involved in his care "given the nature of his professional lifestyle".
Dr Wheeler's defence states that when he took over prescribing the methotrexate, he was aware that Mr Vavalidis was established as stable on a dosage which was effective in controlling his psoriasis without side-effects.
Are regulators doing their job?
Leigh Day's head of clinical negligence, Russell Levy, told BBC News: "I've been specialising in healthcare since 1985, and I'm clear that this is the worst case of repeated, persistent, negligent care that I've ever come across.
"This case also demonstrates the GMC should proceed much more quickly.
"It's quite wrong that 18 months after the death, the family still don't know whether any fitness to practise proceedings will be brought against Dr Wheeler."
Sloane Street Surgery was deemed to meet all five essential standards when it was last inspected by the Care Quality Commission (CQC) four years ago.
The CQC said: "To date, we have not received direct notifications from the GMC, the practice, its patients, or others that give cause for concern about the safety and quality of care within the surgery as a whole.
"We have contacted the GMC regarding Dr Wheeler.
"Also, we have contacted the practice for assurance of how it monitors patients who are on high risk medication.
"We will ascertain whether the practice should have notified us of the unexpected death of the patient, in line with their duties as a regulated body."