A six-figure award to an estranged daughter who was left out of her mother's will has come under challenge at the UK's highest court.
Supreme Court justices have been asked to rule in the latest round of a lengthy legal fight which began after Heather Ilott's late mother Melita Jackson left the majority of her £486,000 estate to three animal charities.
Mother-of-five Mrs Ilott, from Great Munden, Hertfordshire, who has no pension and lived on state benefits, went to court and was originally awarded £50,000 from the estate - but Court of Appeal judges upped the sum to £163,000 last year.
The Blue Cross, the Royal Society for the Protection of Birds and the Royal Society for the Prevention of Cruelty to Animals now argue that the appeal judges "fell into error" in deciding to increase the maintenance payout, which included £143,000 for Mrs Ilott to buy her housing association home.
Seven Supreme Court justices have been urged to overturn the Court of Appeal's ruling and either make an "appropriate" order for Mrs Ilott's "provision", or to restore the order made by a district judge in 2007 that the sum should be £50,000.
Only child Mrs Ilott was rejected by her mother at the age of 17 after she left home without her knowledge or agreement in 1978, to live with her boyfriend Nicholas Ilott, who she later married.
Attempts at reconciliation failed and when 70-year-old Mrs Jackson died in 2004 her will made no provision for her estranged daughter.
Mrs Ilott, who is in her 50s, made an application under the Inheritance (Provision for Family and Dependants) Act 1975 for "reasonable financial provision" from her mother's estate.
The Act confers the right on a child of a deceased parent to apply for an order if a will does not make reasonable provision for their maintenance.
It is the first time that an appeal under the 1975 Act has reached the Supreme Court. The challenge is opposed by lawyers for Mrs Ilott, who attended the London hearing.
The charities say their case before the panel of justices, headed by the court's president Lord Neuberger, is to "affirm the importance of testamentary freedom and secure crucial guidance for the future".
In a statement they said: "The charities have appealed this decision in order to obtain essential clarity from the Supreme Court regarding the scope of the court's power to interfere with a person's testamentary wishes using the 1975 Act."
In 2007, District Judge Clive Million said Mrs Ilott's financial circumstances were ''straitened and needy'', and concluded that her exclusion from the will had been unfair - deciding that the ''appropriate provision'' from the estate was £50,000.
Mrs Ilott challenged the size of the award which led to the increase by three judges in July last year. As well as the £143,000, it was also for the "amount of the reasonable costs of acquisition".
Lady Justice Arden, who announced the court's decision, said: "I would additionally award her an option to take a further maximum capital sum of £20,000 to provide an immediate capital sum from which further income needs can be met. I have expressed the award in these terms in order to preserve her state benefits."
The justices are expected to reserve their decision at the end of the one-day hearing.
Before the hearing, James Aspden, a partner at Wilsons Solicitors who is representing the three charities, said in a statement: "The charities trust that the court will provide essential guidance on the scope of the court's powers under the Inheritance Act and clarify the other important issues this case has highlighted."
In a joint statement the charities said: "We are immensely grateful for the generosity of those who leave a gift to a charity about which they feel passionately.
"Their generosity is vital to the valuable work that we do and we take very seriously our duty to honour the wishes of our generous supporters who choose to remember us in their will.
"We look forward to the resulting clarity that the Supreme Court decision will be able to bring for the charity sector as a whole, and to the renewed confidence that a clear decision at the highest level will give to those making their wills, that their wishes will be respected."
The charities say that in April 2002 Mrs Jackson wrote "a heartfelt letter to accompany her will in which she explained her decision and instructed her executors to defend any attempt by her daughter to contest it".
They said that in the letter she wrote: "If my daughter should bring a claim against my estate I instruct my Executors to defend such a claim as I can see no reason why my daughter should benefit in any way from my estate ... I have made it clear to my daughter during her lifetime that she can expect no inheritance from me when I die".
The justices have been asked to rule on five issues relating to the 1975 Act.
They include whether the appeal judges were wrong to "set aside" the district judge's award, whether they "erred" in taking account of the factual position "as at the date of the appeal rather than the date of the original hearing", and also whether the court was wrong to "structure" an award under the 1975 Act in a way which allowed Mrs Illott to preserve her entitlement to state benefits.
Presenting argument on behalf of the charities, Penelope Reed QC argued that the Court of Appeal was "wrong to interfere" with the discretion of District Judge Million "because his exercise of discretion indicated no error of law, was not plainly wrong and there had been no other procedural irregularity".
She told the justices that the appeal judges "failed to give due weight" to the fact that Mrs Illott had been "independent of the deceased her entire adult life, had been estranged from her and had no expectation of benefiting from her estate".
The QC said they had also "failed to give weight to the testamentary wishes of the deceased".