A coroner has recorded an open verdict in the death of six-year-old Charlie-Bob Townsend, who was found dead in his father's burning home.

Charlie-Bob was discovered by firefighters in the early hours of April 24 last year, shortly before his father Christopher, 51, was found hanged in the garage of the house in Long Ashton.

At an inquest yesterday, assistant deputy coroner Terence Moore confirmed that Charlie-Bob had died before the fire took hold and was probably smothered by a pillow, after hearing evidence from a postmortem examination.

But he rejected an unlawful killing verdict because he could not be sure beyond reasonable doubt that "another natural cause" had not been responsible for Charlie-Bob's death.

He recorded that Mr Townsend had taken his own life.

After the hearing at Flax Bourton, Charlie-Bob's mother Paula Hey said she felt that the verdict did not reflect what had happened to her son.

Miss Hey said: "In my heart of hearts, I know my son was smothered by his father. How much more evidence do you need? There wasn't another person there at the time.

"Charlie was such a lively, energetic, sweet child. He didn't deserve to lose his life, it was such a tragic loss."

A set designer for the BBC's medical drama series Casualty, Mr Townsend met Miss Hey, who also worked for the BBC, in 1999 and they were married a year later.

In 2006, the inquest heard, they began to have problems and reports of domestic incidents were made to the police.

They separated and a custody battle began over Charlie- Bob and Miss Hey's son from a previous relationship, Louis.

The court was told Mr Townsend was "devastated" at the thought of losing access to Charlie-Bob.

In a statement, a friend of Mr Townsend's, Sophie Becher, said: "He became obsessed with fighting his corner. He was increasingly frustrated by the lack of progress in court; he felt it was going nowhere."

The inquest heard the deaths occurred hours after a family court hearing on April 23, 2008, at which Mr Townsend had mistakenly thought he had lost his children.

Another of his friends, Elizabeth Ashmead, said: "He said he just came out of court crying, he said he had to sign over his home, he couldn't have Charlie-Bob on Wednesdays any more.

"He said 'It's time to sling the noose'. I said 'Absolutely not'."

The family social worker, Geraldine Thomas, said Mr Townsend had misunderstood the outcome of that hearing.

She said: "It hadn't got to a final hearing, Mrs Townsend wanted to change the contact but I don't think that's what he heard.

"He said 'Thank you for your assistance but this is the end'. It wasn't out of character for Chris, he would often make very dramatic statements."

Firefighters discovered Charlie-Bob's body under a duvet after being called out to Mr Townsend's home in Long Ashton Road at about 6am the following morning.

No suicide note was found with Mr Townsend but a picture of Charlie-Bob was found on a pile of family court papers at the bottom of the garden.

Pathologist Dr Hugh White said Charlie-Bob died before the fire started.

He said: "There was no soot stain on his tongue, inside of his mouth or his airways. The carbon monoxide level was normal."

There were no traces of alcohol, drugs or sedatives in the boy's system.

Dr White said: "There was no pathological evidence to confirm asphyxiation, but the most probable cause of death was smothering with a pillow."

But because of the lack of "definitive evidence" to confirm this opinion he recorded cause of death as "unascertained".

Recording his verdicts, Mr Moore said: "There is undoubtedly circumstantial evidence that Charlie-Bob's death was not from natural causes. I've considered a verdict of unlawful killing but rejected it. The evidence leaves a reasonable doubt."

A statement from Mr Townsend's family read: "Chris was an extremely kind and loving step-father, son and brother, most generous with his time and patience.

"He and Charlie-Bob were much loved and will be greatly missed by the family and many good friends."