A judge has told two brothers in their 40s that they can no longer have control of their sick mother's finances.
Both men had been given a power of attorney after their mother, a former university lecturer in her early 70s, was diagnosed with dementia.
But Judge Denzil Lush ruled that the brothers had contravened their authority - and he decided that the woman's partner, who is in his 60s, should take the control.
Detail of the case has emerged in a written ruling by the judge following a hearing in the Court of Protection - where issues relating to sick and vulnerable people are analysed - in London.
He did not identify the family. He said the woman was cared for in a nursing home in Leicestershire, her elder son lived in Northamptonshire and her younger son in Leicester.
Judge Lush said officials from the Office of the Public Guardian, which protects people who lack the mental capacity to make decisions about health care and finance, had raised concerns.
They told him that the elder brother had a farm and had used nearly £20,000 of his mother's money to buy farm supplies and invested another £24,000 in a biomass boiler.
The elder brother said his younger brother had no dealings with their mother's financial affairs.
He said he had had looked after her affairs to "the best of my ability".
Judge Lush said both brothers had "behaved in a way that contravenes their authority".
The judge said the elder brother had "benefited" and failed to "act with honesty and integrity".
And the younger brother had "failed to safeguard" his mother's finances.
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