Appeal judges have cleared a mum of murdering her toddler son - but without saying why.

The mummified body of little Declan Hainey - who should have been celebrating his fifth birthday today - was found in a squalid flat in Bruce Road Paisley.

By the time doctors were able to examine the child, it was impossible to tell how he died. But Kimberley Hainey, 38, was found guilty of murdering her son and jailed for life.

Hainey came to the Court of Criminal Appeal in Edinburgh in January seeking to overturn the conviction which earned her a minimum sentence of 15 years.

Defence QC Edward Targowski QC argued that crucial evidence heard by the jury was flawed.

The lawyer questioned the claims expert witnesses called by the Crown who said that tell-tale marks on his bones were signs of malnutrition.

The murder charge alleged that heroin addict Hainey had abandoning her son for long periods of time without food or drink while she partied, drank and took drugs.

At a brief hearing today, judge Lord Clarke announced: "The court has come to the conclusion that the conviction of the Appellant (Hainey) of the murder of her baby son, Declan ... must be quashed."

Lord Clarke went on to say that during the appeal judges' consideration of the question, issues had arisen which has nor been discussed during the hearing in January.

Because of that, the appeal court will hear from lawyers tomorrow before the judges reveal why they have overturned the murder conviction.

Hainey was also convicted of attempting to pervert the course of justice by keeping Declan's body hidden, knowing that she had murdered him - but no grounds of appeal have been put forward on that charge.

The jury at her trial at the High Court in Glasgow rejected Hainey's claim that she had woken one morning to find Declan dead in his cot and had not reported the tragedy because, as defence QC Edward Targowski explained: "She simply went into a downward spiral."

By the time tragic Declan Hainey's decomposing body was found in March 2010 - just before his second birthday - he had not been seen alive for eight months.

A six-week trial at the end of 2011 heard how Hainey had kept family, neighbours and social services at arm's length - not allowing them to get close to the little boy.

After Declan's death, Hainey sold his clothes and toys to buy heroin. The jury were shown photos of rubbish, dirty clothes and nappies littering the squalid flat.