The parents who suspect their seven-year-old son died from cyanide poisoning when their home was hit by the severe floods in February will march on Spelthorne Council today [October 21], to demand answers over the cause of his death.
Zane Gbangbola died the day after serious flooding hit Chertsey in February.
Both his parents were also taken to hospital after suffering from the effects of hydrogen cyanide, which they claim leaked from a landfill site near to their riverside home.
His father Kye Gbangbola has been left a paraplegic due to exposure to the gas.
A pathologist report initially stated Zane's cause of death was "inconclusive", but after further tests it was changed to "carbon monoxide poisoning", linked to a faulty petrol-driven pump - a decision his parents have always denied as they said they never used the pump in their house.
The Environment Agency and the local council were aware of potential risks of ground gas from an old landfill site next to the family's home, it has been claimed.
His parents are now demanding a full investigation into the landfill site, accusing the police and authorities of "a cover-up".
Nicola Lawler, Zane's mother, said: "21 October marks Zane's birthday, and this is the day we will take our petition to the council. As parents we can't share happy birthday celebrations with our precious son, but we can give him a gift of truth.
"Without an investigation into landfill during floods there can be no guarantee that this won't happen again. It's time for change so that agencies do their jobs properly and protect the public."
The Environment Agency told the Daily Mail it built a gas-proof membrane, which it argued was "entirely appropriate as a purely precautionary approach", at a cabin four years ago next door to the family's house.
An EA spokesman said: "In 2010 we built the property with standard damp-proofing protection as it's a timber structure on low-lying ground.
"Our sincere sympathies continue to be with the Gbangbola family and we are cooperating with the investigation fully."
Surrey Police said: "We are conducting further enquiries to establish whether there is any liability or criminal offences in respect of the hire company who provided [the pump] and we have submitted a file to the Crown Prosecution Service."
The march led by Zane's parents and other residents will set off from Spelthorne Leisure Centre car park at 1pm and will continue to the council offices.
More than 15,000 people have signed a petition demanding the 'Truth About Zane'. The Zane Gbangbola memorial fund has also raised nearly £14,000 to find out the circumstances behind how the youngster died.