But after the trial, a psychiatrist who had treated the defendant, Mark Henry, criticised mental health regulations which had failed to prevent Henry carrying out the attack.
Dr Pamela Bowling added that Henry's parents had been campaigning for five years to obtain proper treatment for their son.
At an earlier hearing, the jury was told that Henry, 25, had ambushed Doris Thompson, 46, a businesswoman and voluntary church worker as she loaded her BMW car in the car park of Sainsbury's in Wandsworth, south-west London, last July. He hit her 'two or three times' about the head. The court was told Mrs Thompson, of Victoria Square, Belgravia, central London, was fortunate to have survived the attack.
Henry, of Kilburn, north-west London, had previous convictions for assaults, threatening behaviour and possessing offensive weapons, but before the baseball bat attack no court had sent him to a psychiatric hospital.
Atthe earlier hearing, he was convicted of causing grevious bodily harm with intent to Mrs Thompson and of affray in relation to a threatened baseball attack on a second woman.
The Common Serjeant of London, Judge Neil Denison, said doctors disagreed about Henry's precise mental condition. He said there was no bed available for him in an appropriate hospital and therefore a prison sentence had to be passed. However, if Henry's condition deteriorated while he was in jail, he could be transferred to a mental hospital.
Since the attack, Henry has been responding to treatment at the Neasworth Hospital, in Royston, Hertfordshire, where he has been treated by Dr Bowling. The judge was told Henry wanted to stay there, but doctors had expressed fears that the hospital was not secure enough.
Outside court, Dr Bowling said: 'This is a classic case where the professionals should listen to the parents.' Dr Bowling added that doctors had failed to ensure that Henry was properly treated and that the public was protected from him.
'This highlights a problem with the mental health system. It is reactive rather than preventitive. It is only after someone has done something terrible that the full weight of the system is brought into operation,' Dr Bowling said.
The difficulty faced by doctors in Henry's case was that his illness was extremely difficult to diagnose and he was able to hide it well. He suffered from a rare form of mental illness which affected his emotions and thought processes. The conditions were 'slow and insidious' and they gradually eroded his personality, Dr Bowling said.
She told the court: 'He is a danger to the public. He is at the beginning of his illness career. He is capable of extreme violence and there is a possibility his condition will deteriorate further.'
Henry's father said after the trial that he was very unhappy at the way his son had been treated. He said that he feared the drugs which had helped his son in the past few weeks would no longer be available to him in prison.