Heather Ilott has been awarded £164,000 by the Court of Appeal following a lengthy legal battle after she was initially left nothing by her mother Melita Jackson, who died in July 2004 at 70.
Mrs Jackson wished her net estate of around £486,000 to be split between The Blue Cross, the Royal Society for the Protection of Birds and the Royal Society for the Prevention of Cruelty to Animals, with no provision for her only child.
The pair had been estranged for 26 years and several attempts at reconciliation had failed, the court heard.
The appeal judges ruled in Mrs Ilott's favour, stating her income was "not reasonable" for her maintenance and future, as she was on benefits and had no pension. Mrs Jackson had "no connection" with the charities during her lifetime, they added.
She was awarded £143,000 to buy her rented home from a housing association and a further £20,000 in cash as "additional income".
Law experts have warned more wills could be challenged by surviving adult children following the ruling.
Gary Rycroft, a member of the Law Society's wills and equity committee, told the Daily Telegraph: "This ruling is saying that while you can still disinherit your children, you are going to have to explain why and show connections with those you are leaving the money to.
"It is also very important because it seems to be making it easier for adult children to claim for reasonable financial provision in wills and has made the gap wider for them to do that."
Mrs Jackson had been estranged from her daughter since 1978, when, aged 17, Mrs Ilott left home without her mother's knowledge to live with her soon-to-be husband Nicholas Ilott.
The couple have five children, one of whom is set to be the last to leave the family home in Great Munden, near Ware, Herts, to go to university. They earned "very small incomes" and their monthly expenses were "modest", showing no items of clothing, holidays or gifts, the judges said.
Mrs Ilott, who was raised by her mother after her father died before she was born, first challenged the will under the Inheritance (Provision for Family and Dependants) Act before District Judge Clive Million who found that it did not make reasonable provision for her.
He ordered that she should have £50,000 from the estate.
Mrs Ilott then asked the High Court to increase the sum but Mrs Justice Parker upheld the earlier decision, before Mrs Ilott pursued the case to the Court of Appeal.
In a judgment handed down yesterday, Lady Justice Arden said: "This is a case where the court can and should make reasonable financial provision out of the deceased's estate for the appellant's maintenance so that her living expenses are relieved without affecting the state benefits on which she relies."
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