An inquest to determine the cause of seven-year-old schoolboy Zane Gbangbola’s death has now been set for almost two years after he died.

Friends and family this morning filled every chair at Woking Coroner’s Court for a pre-inquest review into the death.

About 10 people from the Truth About Zane campaign group gathered at the front of the court before the hearing with placards demanding answers. They wore red and orange flowers, Zane’s favourite, to symbolise the campaign.

In February of last year Zane, who attended St George’s Junior School, Weybridge, was taken to hospital with his mother Nicole Lawler, 37, and father Kye Gbangbola, 48, after being overcome by fumes when the basement of their £1m riverside property in Chertsey filled with floodwater.

His parents believe the poisoning was due to contaminated water from a landfill site near Chertsey.

Today, coroner Richard Travers was keen to understand if the argument of cyanide poisoning, which Zane’s parents are adamant was the cause of death, held enough evidence to be pursued as a line of enquiry in the inquest.

He asked: “What is the link if there was hydrogen cyanide there, what is the link that that hydrogen cyanide contributed in a material way to Zane’s death?

“At the moment, experts [who gathered to discuss Zane’s death last April and concluded the cause was from carbon monoxide] seem to be saying actually it wasn’t hydrogen cyanide, it was carbon monoxide.”

Zane’s parents Kye and Nicole said in a statement: "This was an important step towards revealing the truth about what happened to Zane. We now hope for a full and proper investigation into his death.

"We are grateful to our legal team for their work so far.

"We should never lose sight that this is about a little seven-year-old boy, Zane Gbangbola, who died needlessly.

"The Truth About Zane campaign has been arguing that the care of people and public protection is paramount.

"Today Zane should be enjoying his last day of school before the summer holidays but instead we’ve had to endure a pre-inquest hearing into his death."

Zane was found to have 8 per cent carbon monoxide levels in his bloodstream. Fatal levels are usually around 50 per cent.

Leslie Thomas QC, representing the family, said: “No carbon monoxide was found at the property. It was tested for and none was found. The only evidence of a noxious gas that was detected was hydrogen cyanide.”

He said the experts who gathered to discuss Zane’s death “were significantly troubled” to feel the need to meet.

He said tests for hydrogen cyanide poisoning should take place within a certain time limit, and said the wrong tests were originally carried out.

Ivor Collett, representative for Spelthorne Council, argued there was no evidence to suggest Zane’s death was due to the presence of hydrogen cyanide.

He said: “It would have to be some evidence, some real evidence of a link, and at the moment there is none.”

A recording of gas levels taken by a firefighter on the evening Zane became ill showed there was hydrogen cyanide present in the house. Mr Collett said this equipment was often faulty.

Mr Gbangbola, who was paralysed from the waist down following the flooding, said of his son: “Anyone who knew our Zane will know exactly why we need to get to the truth.

“He was an incredibly bright, generous, happy and life-loving boy who had such a wonderful future ahead of him. We cannot let his death be in vain.”

Police said Zane died from carbon monoxide, but his parents said this was impossible because their house was fully electric. Surrey Police investigated and found no criminal charges would be brought over Zane’s death.

Mr Travers finally concluded he would not rule out the evidence and discussions surrounding hydrogen cyanide.

In addition to the three interested persons already recognised by the coroner, following submissions from counsel, Mr Travers approved three more in today’s hearing.

These six will then make further submissions to the court at a later date, before the inquest begins on Monday, January 18, 2015. Mr Travers directed the inquest would not be heard on February 8 or 9, if it continued to those dates, to allow for the two year anniversary of Zane’s death.

It is still to be decided if the inquest will be heard by a jury.

Mr Thomas said: “This has significantly impacted on my clients' lives, not just because they have lost a child, but the father has been severely disabled.”