A leading neuropathologist who conducted an examination on Zane Gbangbola’s brain had not been told about the levels of hydrogen cyanide in his home, an inquest has heard.

Zane, seven, a pupil at St George’s Junior School in Weybridge, died after his family home in Thameside, Chertsey, was flooded on February 8, 2014.

He had been sleeping in the spare bedroom after watching television with his mother Nicole Lawler.

His family claims he was killed by hydrogen cyanide gas that leaked from a former landfill site behind their home, but this is disputed by Spelthorne Council and the Environment Agency.

Low levels of carbon monoxide were found in Zane's blood during a post-mortem examination, which concluded that this was the cause of his death.

Read more: Zane Gbangbola family home 'not safe to live in' because of gas risk, inquest hears

The family had bought a number of electric pumps to remove floodwater from their home and later rented a petrol-powered one as back-up.

Professor Safa Al-Sarraj, a consultant neuropathologist, produced a report on April 24, 2014 following an examination of Zane’s brain and spinal cord. His report contributed to the final post-mortem examination result.

He noted that there was swelling in the brain and a slight pink discolouration, which “could be caused by lack of oxygen, commonly seen in carbon monoxide poisoning”, on July 11 at Woking Coroner’s Court.

He added that damage to the cortex could be caused by either “toxic damage by carbon monoxide or toxic damage by drug overdose”.

He concluded that the damage was “suggestive of carbon monoxide” poisoning.

But when asked by coroner’s counsel Alison Hewitt if the findings were consistent with hydrogen cyanide poisoning, he told the court he had not been told “anything other than the carbon monoxide levels”.

Leslie Thomas QC, representing Zane’s mother Nicole Lawler and father Kye Gbangbola, said: “When you look at other clinicians in this case, they put a huge deal of reliance on what you say.

“If you haven’t been provided with the relevant information, everybody else relying on what you say isn’t relying on a full report.”

Prof Al-Sarraj agreed, saying had he been told about the hydrogen cyanide levels in the house he would have analysed the brain from that perspective.

He took half an hour to reflect on online medical journals to come to an understanding whether hydrogen cyanide could cause similar effects.

Addressing the court, he said there would be similarities between carbon monoxide and hydrogen cyanide poisoning, but said there was no evidence in the journals that links discolouration in Zane’s brain to hydrogen cyanide.

He added that “on the balance of probabilities”, hydrogen cyanide poisoning could be ruled out.

But Mr Thomas challenged his evidence with a medical journal that studied two people who had died from hydrogen cyanide poisoning, where there was no damage to the brain, but changes in colour to that particular part of the brain can occur.

Prof Al-Sarraj said he would take two days to produce a new report having looked more closely at medical journals referring to hydrogen cyanide poisoning in the brain.

The inquest continues.