Relatives of a woman killed by carbon monoxide poisoning spoke of their devastation as the manslaughter trial of a gas engineer collapsed today.

Christopher Jilbert was cleared of killing Angela Pinkney after the Crown Prosecution Service offered no evidence against him before the start of his trial at Oxford Crown Court.

British Gas engineers Mr Jilbert, 50, and his colleague Peter Woelki, 53, were charged with manslaughter after Miss Pinkney's death in March 2005.

The case against Mr Woelki was dropped in April.

Paul Reid, prosecuting, said Mr Jilbert did some work on the boiler two days before Miss Pinkney's death.

He said: "In order to bring this case against Mr Jilbert, the Crown would have to prove that when he attended he adjusted the air-gas ratio valve on the boiler.

"We cannot prove that Mr Jilbert adjusted that valve on the day in question.

"It cannot be proven he is criminally negligent and caused the death of Miss Pinkney."

Miss Pinkney, 35, an administrative officer for Oxford University, died in the bedroom of her home in Mandelbrote Drive, Littlemore, just hours after being sent home from hospital where she had been treated for nausea.

Speaking after the case, father-of-three Mr Jilbert, of Bayswater Farm Road, Barton, said: "I am very relieved but also angry and disappointed. It has been a very big pressure on my family. I had to give up my job."

Mr Jilbert, a gas engineer since 1974, said he had been worried about the trial and had feared being sent to jail.

His wife Lesley, 46, added: "I just want to get the family back together and get on with our lives."

Father-of-three Mr Woelki, 53, of Poplar Grove, Kennington, said: "It has been a nightmare. I think the authorities have handled the case really badly.

"For two-and-a-half years we have been prosecuted and there was never a case to answer. It has affected my family and everybody. I was suspended for a period of time but I went back to work a couple of months ago.

"I am quite angry at the whole way the thing was done."

Speaking after the case, Miss Pinkney's mother Heather, 73, and brother Mike, 42, both of County Durham, said they were devastated no one would be held accountable for Angela's death. They called on people to have carbon monoxide alarms fitted and said they would like stricter building regulations.

Mrs Pinkney said: "I am devastated no one has taken responsibility for her death.

"It seems nobody is to be held accountable."

British Gas said in a statement: "Our customers' safety has always been our foremost priority and we believe our engineer training, monitoring and support procedures to be of a very high standard."