Mrs Knowlson, 68, had been jailed for 28 days on Monday because she would not stop feeding birds with bag-loads of environmentally unfriendly bread.
Yesterday, she appeared at the High Court and promised Mr Justice Buxton, who had jailed her, that she would comply with the orders in future.
The judge authorised her release and she left Holloway Prison shortly after noon. Her head was covered by a blue anorak as she was escorted to a waiting taxi by her solicitor.
However, she was unable to return to her old address in Purley Oaks, south London, where she looked after a retired draughtsman, Alan White, in exchange for free accommodation.
Mr White, 66, who took Mrs Knowlson in five years ago after she was evicted from another home, said he could not house her again because he suspected she might be mentally unbalanced and needed help.
Council officials in Croydon were arranging for temporary bed and breakfast lodgings while an application was made for permanent housing. Mrs Knowlson, a bird lover for 30 years, had been warned repeatedly that the food she scattered, and the ensuing droppings, were a serious health hazard and likely to attract rats. She said that when she "looked at their little faces" she could not resist feeding the hundreds of pigeons that flocked to her.
Mrs Knowlson, dressed in a cream cardigan and patterned dress, had repeated coughing fits as she sat at the front of the court yesterday. Her counsel, Mark Whalan, told the judge that she had been sufficiently punished and that further incarceration was not necessary.
Mrs Knowlson had told him about the conditions in Holloway and the distress it had caused her. "Bearing in mind her age and disability, the last four days have profoundly affected her." On Tuesday, she had been moved into the prison's hospital wing.
Mrs Knowlson whispered "that's right" and "yes" when the judge asked her whether she was clear that she was not going to break the orders again.
Mr White said later: "She has a kind heart but she is very mixed up." The pigeons were starting to disperse from the house, he added.Reuse content