Hindley, 56, is appealing against the decision of three successive Home Secretaries, including Jack Straw, to keep her in prison for the rest of her natural life despite the recommendation of her trial judge that she serve 30 years. She has been in prison since 1966.

The hearing began on Monday and is expected to last three days although judgement will probably be reserved to a later date.

Rose West...one of 26 given "whole life tariff"

The Yorkshire Ripper, Peter Sutcliffe, serial killer Dennis Nilsen and Gloucester multiple murderer Rose West are among a group of 26 other "Category A" criminals who have also been told they will never be allowed out of jail.

All are believed to be taking a keen interest in the outcome of this week's hearing at the Court of Appeal.

'Locked up because of notoriety'

Hindley's lawyer, Edward Fitzgerald, QC, told the court on Monday she had been unfairly locked up for life "because of her notoriety and unpopularity".

Jack Straw: Life should mean for life

He said there was evidence that she was completely rehabilitated and no longer presented a danger to the public. But he said Mr Straw and his predecessors had bowed to public opinion, which has consistently called for her to be kept behind bars.

Hindley, who is held at Highpoint Prison in Suffolk, was convicted of murdering Lesley Ann Downey, 10, and Edward Evans, 17.

Ian Brady...insists Hindley was his willing accomplice

She and her lover Ian Brady, now 60, were also found guilty of murdering 12-year-old John Kilbride.

Both have subsequently admitted killing Pauline Reade, 16, and Keith Bennett, 12, whose bodies were also buried on Saddleworth Moor on the edge of the Peak District overlooking Manchester.

Mr Fitzgerald accused Mr Straw of contravening the purpose of the parole system, which states no category of prisoner can be excluded from parole.

'Murder by duress'

He said the Home Secretary had also ignored her claims that she had coerced into taking part in the killings by Brady.

In 1987 Hindley said Brady had raped her and threatened her family.

Mr Fitzgerald said she had been throttled by Brady on one occasion.

He told the three appeal judges, headed by Lord Woolf. equally horrific crimes had been committed by others but had not attracted a life sentence because they had lower profiles.

Last year three High Court judges, led by Lord Bingham, the Lord Chief Justice, rejected her lawyers' argument that a provisional minimum tariff of 30 years had been unlawfully increased by Michael Howard and Mr Straw.

Supporters say Hindley, pictured in jail, has changed

In a 35-page judgement Lord Bingham ruled that home secretaries had the power to decide that a life sentence can mean life.

But he did not rule out that one day Hindley could be released "in exceptional circumstances", and also gave her leave to appeal.

In August, Brady wrote an open letter to Mr Straw saying he was ready to release letters from Hindley in which she planned an attack on a child.

The move was seen as a direct attempt by him to frustrate her bid for freedom.

He maintains she took part in the killings without coercion.