Great Ormond Street Hospital for Children was unlawfully deprived of a £200,000 bequest under a retired nurse's will when she fell under the "undue influence" of her housekeeper, a High Court judge ruled in London yesterday.

Lily Morris, who died aged 74 in April 1997, had once worked at the London hospital and left it half her estate in her will. But she became so dependent on Pauline Rushin and her daughter, Caroline Billinge, that she signed over her £300,000 house to Mrs Rushin and made other gifts, including two cars, said Mr Justice Rimer.

Mrs Rushin imposed barriers between Mrs Morris and her family, he said, and in the end Mrs Morris "stayed almost exclusively in the company of those on whom she had by now become wholly reliant and dependent". He said the events leading up to Mrs Morris signing away Home Farm House, Idridgehay, Derbyshire, gave rise to a presumption that the deal was induced by the undue influence of at least Mrs Rushin and probably her daughter.

He ruled that Mrs Morris did not have sufficient capacity or understanding to enter into such an agreement because she was suffering from serious delusion and mental disorder caused by Alzheimer's disease.

In a case brought by the hospital's trustees, the judge set aside the "highly imprudent" house transfer and the other gifts and ruled that they formed part of Mrs Morris's estate. The hospital is entitled to half of the estimated £400,000 bulk of the estate under the will.

Mrs Rushin, of Kniveton, Derbyshire, and her daughter had strongly contested the case, arguing that the love and affection between them and Mrs Morris prompted her to make the gifts entirely of her own free will. They denied her mental health had deteriorated.

Mrs Morris and her late husband had bought the house in 1977; they had no children. She died when she was strangled by clothing that became trapped in a stairlift at her home.