The RSPCA has challenged a ruling which overturned a will leaving it a £2 million estate.

University lecturer Christine Gill, from Northallerton, North Yorkshire, won a High Court battle last year to overturn the will which left her parents' 287-acre farm to the charity.

In a ruling given in Leeds, a judge found that Dr Gill's "domineering" father had coerced her mother into making the will.

But the findings of Judge James Allen QC have been appealed against by the RSPCA during proceedings before the Master of the Rolls, Lord Neuberger, sitting with Lord Justice Lloyd and Lord Justice Jackson in London.

Elspeth Talbot Rice QC, for the RSPCA, told the court that one of the issues for decision was whether the judge was "wrong to find that Mr Gill unduly influenced Mrs Gill into executing her will". Another question was whether the judge was "wrong to find that Mrs Gill knew and approved of her will".

Judge Allen said it would be "unconscionable" if Dr Gill did not inherit Potto Carr Farm, near Northallerton, where she voluntarily helped out during her spare time over a period of more than 30 years.

Mr Gill died in 1999, aged 82. It was only when her mother died in 2006, also aged 82, that Dr Gill saw the will, in which her parents had left the farm to each other and then to the RSPCA when both died.

The judge found that Dr Gill's mother had wanted her daughter to inherit the farm but Mr Gill - who he described as a "bully" - had exerted pressure over his wife to favour the RSPCA.

The appeal is being closely watched by other charities who say they are "very concerned at its possible implications for the charity sector".

The RSPCA said in a statement: "The Gills had already provided substantially for their daughter during their lifetime, which included a large contribution towards the purchase of the farmhouse in which she now lives. The RSPCA carefully considered the merits of its action before taking the decision to defend Dr Gill's claims and subsequently to appeal in order to honour Mrs Gill's wishes."