A mother has paid a heartbreaking tribute to her 10-year-old son who died unexpectedly after being prescribed an opiate drug by a Queen Elizabeth Hospital doctor.

At the inquest into the death of Thomas Warren, who was diagnosed with cerebral palsy in 1999, Jane Warren held back tears as she told Southwark Coroners Court her beloved son “could charm the birds out of the trees.”

Thomas was rushed to the hospital following an apparent reaction to drug Fentantyl, which was prescribed by a locum doctor following extensive hip surgery, days before his death in November 2008.

Mrs Warren, who broke down in tears after giving evidence, said: “He had big blue eyes and a gorgeous smile.

“He never let his disability get him down and tried hard to deal with things like a normal boy. We miss him dreadfully.”

Thomas, who was born October 4 in 1998, had a twin sister Megan and coached his school football team despite also suffering from scoliosis.

At the time her son was prescribed the drug, Mrs Warren claims she witnessed the pharmacist arguing with the doctor, who cannot be named for legal reasons, and protesting against prescribing the medication.

The doctor who supplied the drug failed to attend the inquest at the request of his psychiatrist who in a report stated he was mentally incapable to cope with the stress of the courtroom.

Mrs Warren painfully described the events leading to his death on that fateful day.

She said: “Tom woke up at 8.30am to watch TV and said he felt queasy. He complained of pain and kept falling asleep which was out of character for him.”

The mother claims to have tried effortlessly for days to make contact with her doctor to bring an appointment date forward which she had booked previously for her son following concerns for his wellbeing.

Mrs Warren then said she checked on her son soon afterwards and noticed he had stopped snoring and his lips were pale.

After being rushed to hospital, staff told the parents their son would not survive and subsequently turned off the ventilator.

She eventually received a call back from the doctor, regarding the appointment, shortly after Thomas died.

The inquest continues.