AN inadequate mother who shook her three-week-old son to death was freed yesterday after appeal court judges quashed her three-year jail sentence.

Carol McIsaac, who admitted the culpable homicide of her son Shane, has now been placed on probation for two years with a condition that she take part in psychological counselling to help with her anxiety and depression.

She may also receive help to cope with her anger control and poor parenting skills.

After yesterday's decision at the Court of Criminal Appeal, McIsaac's solicitor, Mr Michael Gray, said: ''The loss of Shane was a tragedy which has deeply affected the family and that obviously includes Mrs McIsaac herself.

''The purpose of this appeal against sentence was to recommend that a probation order be substituted for the remainder of the sentence which would allow Mrs McIsaac to receive professional assistance and guidance in dealing with the difficulties she had.

''There is a growing acceptance that this type of problem arises in many cases through lack of ability in coping rather than evil intent. Mrs McIsaac is such a case and she now wishes to proceed with the programme of psychological treatment.''

McIsaac's husband, Mr Ronald McIsaac, said he was ''absolutely thrilled'' at the outcome which would mean his wife could return home and allow them to make a fresh start.

McIsaac was jailed in October last year after pleading guilty to assaulting Shane on April 28 1997 at the family home in Hillwood Crescent, Ratho Station, Midlothian, by shaking him vigorously, causing such severe injuries that he died in hospital three days later.

Lord Bonomy was told at the High Court in Edinburgh that after Shane was born there were difficulties with bottle feeding him. He was not a good sleeper, often cried at night and both parents found it difficult to cope.

On the day of the shaking, the baby was again distressed and McIsaac shook him violently before putting him down in his pram. When Shane's father picked him up he found that he had gone limp. He gave Shane mouth-to-mouth resuscitation and ran to call an ambulance.

Shane was taken to St John's Hospital in Livingston where his head was found to be swollen. Doctors thought he was either suffering from meningitis or the victim of a non-accidental injury.

He was placed on a ventilator and transferred to the Royal Hospital for Sick Children in Edinburgh but the life support machine was switched off on May 1 when he was pronounced brain dead.

Lord Bonomy told McIsaac: ''It causes me great sadness to send you to prison but I have to do that because what you did was cause catastrophic injuries to your infant son by shaking him in a temper.''

While psychiatric reports indicated that she accepted the fact of Shane's death, there was no indication that she accepted that she was to blame. The judge felt that a jail sentence was the only way of bringing home to the accused the enormity of what she had done.

Miss Margaret Scott, defence counsel, told the appeal court that McIsaac suffered from learning difficulties and had trouble coping with life. She was on the borderline of being mentally handicapped.

She added: ''This is not a woman who is violent and dangerous and not a woman who is evil. She is a woman who is clearly inadequate and who needs psychiatric help. There is no question that she didn't love that child. She has great difficulty in coping with what she herself has done.''

On the day of the incident her loss of temper had been triggered by an inability to cope under stress.

Miss Scott told Lord Cullen, the Lord Justice Clerk, who heard the appeal with Lords Coulsfield and Allanbridge, that since the incident McIsaac's daughters, aged six and four, had been taken into foster care and had visited her in prison.

During her time in jail it had become clear that she now accepted responsibility for what she had done and she had already served the equivalent of an 18-month sentence.

Lord Cullen said it had been difficult for the appeal court to decide the correct course to adopt in a case which the trial judge had described as an anxious one.

''We have come to the conclusion that in the particular special circumstances of this case it is right for us to take the course of quashing the sentence imposed and substitute a probation order.''

In view of the reports they had received, the appeal court was prepared to place McIsaac on probation during which she would be under social work supervision and take part in psychological counselling as required.