Alex Gray followed the singer for seven years, writing a series of abusive letters, accusations and suicide threats to her house, her sister's house, her management and record company.
Gray was charged after an incident in October 2015 where he burst into Allen's bedroom, walking away with her handbag. He was convicted in April this year of one count of burglary and one count of stalking involving serious alarm or distress, reported Digital Spy.
"I can't help but think that as funds are cut and our health service declines, we will see more examples where innocent people get hurt."
Allen previously said that she was not "angry at Alex Gray", adding: "He has a mental illness. The system has failed him. But until he gets the right treatment and the right help he needs, then I'm not safe."
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She told Newsnight that she felt "victim-shamed" and argued that police did not take her concerns over the handling of the case seriously.
"What I've seen, I think it's terrible the way she has been treated," said Michelle Gray, Alex's mother.
"It hasn't been taken seriously either. This could have been stopped before it got as bad as this.