A mother who killed her brain-damaged son by injecting him with heroin has lost an appeal against her conviction.

Frances Inglis, 57, of Dagenham, Essex, was ordered to serve a minimum of nine years in prison in January this year after being found guilty of murdering Thomas Inglis, 22, in November 2008.

Three judges in the Court of Appeal in London today rejected her conviction challenge but did reduce her minimum prison term to five years.

Delivering the ruling, the Lord Judge said: “There is no doubt at all that the appellant was subjected to great stress and anguish, but dealing with it briefly and starkly, there was, as our analysis of the evidence underlines, not a scintilla of evidence that when the appellant injected the fatal dose of heroin into her son she had lost her self-control.”

He indicated that no exceptions to the law on murder could be made for mercy killings.

“We must underline that the law of murder does not distinguish between murder committed for malevolent reasons and murder motivated by familial love,” he said.

“Subject to well-established partial defences, like provocation or diminished responsibility, mercy killing is murder.”

Mr Inglis suffered brain damage after falling out of a moving ambulance in July 2007. His mother tried unsuccessfully to end his life two months after the accident while he was being treated at Queens Hospital in Romford.

She was successful on her second attempt when she superglued the door of his room shut at the Gardens nursing home in Hertfordshire and gave him a lethal injection of heroin.

Mrs Inglis’ barrister told the court she was convinced her son was suffering from “pain and terror”.

The QC told judges: “In her eyes what she did was end his life in a calm and peaceful way and not one that would cause him pain and suffering and agony.”