The grieving mum has now pleaded with other youngsters not to risk their lives breathing in the dangerous gas.

She said: 'It just takes one second to do it and it can kill you. It's not worth trying it, just don't do it. Don't even go there, just give it a miss.

'I was so proud to be his mum, it's just such a waste.'

Elaine has waited 14 months for the inquest into the death of her eldest son, James Wells, and is now trying to rebuild her life with her other two children Francesca, 18, and Harry, 14.

Elaine, 44, of Beaufort Close, Lee-on-the-Solent, said: 'It is still so surreal. I know it's been 14 months but it feels like he has been away on a long trip and he is still going to come back.

'I miss his cheekiness and I miss everything about him really. Francesca and Harry are keeping me going at the moment.'

An inquest heard apprentice tiler James, 20, was found lying on the floor by his landlady at the house where he was lodging in Gosport. He was taken to Queen Alexandra Hospital but never regained consciousness.

The inquest was told that several empty butane canisters were found in James's bedroom at Privett Road, Gosport, after his death in June last year.

The port-mortem examination was inconclusive, and, recording an open verdict, coroner David Horsley said he could not be absolutely certain whether James died from butane inhalation, or suffered from Sudden Adult Death Syndrome.

There was no trace of butane in James's body but pathologist Dr Adnan Al-Badri said the nature of the gas means it would probably have evaporated before it could have been detected.

The inquest heard that James suffered cardiac arrest and his brain was severely swollen.

James's mother has no doubt that her son, who had no drugs or alcohol in his system, was killed by the gas.

Mum Elaine said: 'Kids will always want to try these things. I would tell them to stay away from this because it is an instant killer.

'It may look harmless but believe me it is extremely dangerous. My son paid the ultimate price for it.

'If one more person can be saved by hearing about what happened to James than that is a good thing.'