A woman who smothered her three-year-old son to death with a pillow will be sentenced for his manslaughter today.
Tara Haigh was originally convicted of murder at the Old Bailey in November 2008.
But she recently won an appeal against that conviction and three Court of Appeal judges in London substituted a verdict of manslaughter.
Haigh, 24, was found guilty by a 10-2 majority of murdering Billy at their home in Guildford, Surrey, in November 2005 and was jailed for life with a minimum term of 10 years.
Lord Justice Dyson, sitting with Mrs Justice Swift and Mr Justice Sweeney, who ruled that her murder conviction was "unsafe", will today announce the sentence she should serve for manslaughter.
It was argued during her appeal that it was impossible for the jury to reach a "rational conclusion as to the appellant's intent".
Her QC, Robin Spencer, submitted that they could not exclude the possibility that the smothering was momentary and consistent with a lack of intent to kill or cause really serious harm.
When giving the ruling in Haigh's appeal, Lord Justice Dyson said the prosecution had acknowledged that "there was evidence from which the jury could conclude that the appellant snapped and smothered Billy".
He added: "The difficulty for the prosecution was that there was no evidence at all on the basis of which the jury could reasonably decide whether the appellant had the intent to kill or to cause really serious harm on the one hand, or the lesser mental intent which was sufficient for manslaughter on the other hand.
"Without that evidence they could only speculate. We are driven to conclude that the murder conviction is unsafe."
The Old Bailey was told that Haigh was trying to find a boyfriend online within hours of suffocating the boy.
During her trial, Sally Howes QC, prosecuting, said: "An examination of the computer showed that, within a few hours of her son's death, she was accessing messages sent to her by men on the website Girls Date Free."
The court heard that she even arranged a date with one man, posting a message on the website saying her son had died from a tumour behind the ear.