The RSPCA could pay more than £1m in legal costs after losing a high-profile High Court battle to keep a legacy worth around £2m.

The charity was told last week that it must pay most of the costs, which is likely to be around £1m, following its failed legal battle with the will-maker’s daughter, Dr Christine Gill (pictured).

For over two years, Dr Gill, a university lecturer, had been fighting to get part of her deceased parents' £2.3m property which was all left to the RSPCA at her mother’s bequest. Gill claimed her mother had been coerced by her father in to making a will contrary to her wishes.

Gill claimed all attempts at mediation with the RSPCA had failed. The RSPCA argued it was “legally obliged to seek funds under charitable law”.

Judge James Allen QC said the RSPCA had “clearly displayed a lack of enthusiasm in relation to the resolution of the dispute by a negotiated settlement,” and had been “somewhat unreasonable, out of step with the expectation of the court and the underlying spirit of modern procedure”.

He ruled that the animal welfare charity would have to foot the bill for most of Gill’s £900,000 legal costs. The charity will also pay its own costs of £400,000. A detailed written judgement on costs is due this week.

The RSPCA has been granted leave to appeal.

An RSPCA spokeswoman said: "We're still awaiting the final costs order to come down from the judge, as he deferred his decision last week.  Depending on the outcome it will be up to the trustees whether or not to proceed with an appeal."