A caring mother who cuddled her terminally ill son as he committed suicide on his 42nd birthday was shown mercy by a judge yesterday.

Heather Pratten, 63, was allowed to walk free from the Old Bailey after being conditionally discharged for a year.

Pratten, of Rayleigh, Essex, had pleaded guilty to aiding and abetting the suicide of her son, Mr Nigel Goodman.

A tearful Pratten left court without commenting after Judge Graham Boal warned that others would not be treated so leniently.

He told her: ''Let no-one who hears of this case misinterpret my decision. Taking the unusual course I have in a very unusual case should not be regarded by anyone as a precedent.''

He said Mr Goodman suffered from Huntington's disease. Pratten had nursed her husband and another son when they, too, suffered from the disease.

''I believe that you too, in a wholly different way, have suffered enough,'' the judge told her.

He added: ''Human life is precious, many regard it as sacred. It follows that only in the rarest and most exceptional cases can those who contribute to the death of another be sentenced to other than immediate imprisonment.

''But your case is indeed exceptional. Your story is one that would move the hardest of hearts.''

Friends and supporters had described her as a good and caring woman.

''I would add - in view of your plea and frankness to police - that I would regard you as a very brave woman,'' said Judge Boal.

The court was told of the heartbreak the family had suffered over the years because of the hereditary brain disease which causes physical and psychological symptoms and ultimately death.

The mother-of-five's first husband had been in hospital for 10 years before he died. Her son, Philip, later developed the disease in a more manageable form and was now being cared for in a special institution.

However, when Mr Goodman, a gifted artist and independent free spirit, showed symptoms four years ago, he took it very badly, said Mr Antony Chinn, defending.

In his youth, Mr Goodman, of Plaistow, east London, had told people he would shoot himself rather than suffer the same fate as his father.

Mr Chinn said he was admitted to Goodmayes Hospital, Essex, but began to talk of killing himself as he realised he would not be able to look after himself.

He became dependent on drink and was found wandering along the A13 in a dishevelled state.

On his 42nd birthday, on March 31 this year, his mother collected him from the hospital so they could celebrate the day together.

However, as soon as they got to his flat, he unwrapped heroin and begged her not to let him leave the flat alive, said Mr Chinn.

He added: ''She hoped to distract him with a birthday meal but he said, 'the best birthday present for me is to go'.

''They placed his birthday cards out and sang happy birthday together. Mrs Pratten found herself in an impossible position.''

Mr Chinn said Mr Goodman had unsuccessfully tried to inject himself but then took the whole amount by mouth.

''Mrs Pratten was plainly startled and distressed. She loved and cared for him all his life. They lay together for a long time and cuddled.''

Mrs Pratten had delayed calling an ambulance because she feared her son would be resuscitated.

Mr Neil Moore, prosecuting, said the mother and son were seen going to his flat at noon and Mrs Pratten summoned an ambulance just after 7pm.

He said: ''She lay with him and did not intervene as he had asked her to promise she would not.''

A note found in the flat apparently signed by Nigel read: ''I am suffering and I want to die.''