A mother found guilty of killing her severely handicapped daughter by disconnecting her breathing tube yesterday sobbed as the Court of Appeal quashed her manslaughter conviction.

Former psychiatric nurse Julie Watts, 32, was cleared of murder by a Manchester Crown Court jury last September, but convicted of the manslaughter of her 14-month-old baby, Abigail.

Mrs Watts, of Little Hulton, Greater Manchester, who was given an 18-month jail sentence suspended for two years, went to the Court of Appeal in London to urge three judges that her conviction was ''unsafe''.

In court with her husband ,Andrew, she wept as Lord Justice Swinton Thomas, sitting with Mr Justice Connell and Mr Justice Poole, allowed her appeal.

Later she said: ''This whole thing should never have happened. No-one could ever imagine what we have been through.''

Abigail was born with clover leaf syndrome, a skull deformity, which left her brain-damaged, deformed, partially-sighted, deaf, and unable to breathe or feed without help.

At the end of July 1995, staff at the Royal Manchester Children's Hospital responded to Mrs Watts' cries for help and found that the tracheotomy tube had become detached from Abigail's throat. The child suffered respiratory failure leading to cardiac arrest.

Mrs Watts, who has a nine-year-old son and a daughter born in November 1996, has always denied interfering with the tube.

At the Court of Appeal, the three judges ruled that the trial judge, Mr Justice Sachs, had not given a particular direction he should have done in summing up on the issue of manslaughter.

Allowing the appeal, Lord Justice Swinton Thomas said:''We cannot be sure that if he had done so the jury would necessarily have arrived at the same conclusion.''

During the hearing, Mr Richard Henriques QC, counsel for Mrs Watts, had claimed that there was a ''real possibility'' the tube was removed by an unknown third party.