The papers about Hindley's time in prison are held at the the National Archives at Kew.
Dr Clark said the papers showed that Hindley "always had ideas of moving beyond her station".
Hindley and Brady were convicted of the murders of Lesley Ann Downey and Edward Evans in 1966.
However, he said the papers showed that Hindley did not "do anything that she didn't want to do".
So even if Miss Hindley has her original tariff restored, her fate still lies in Mr Straw's hands.
Hindley and Brady, the "Moors murderers", killed five children and buried their bodies on Saddleworth Moor, near Manchester.
Inspectors found Hindley Young Offenders Institution (YOI), near Wigan, Greater Manchester, was doing some good work to help inmates.
In 1982, Lord Lane, the Lord Chief Justice, recommended that Miss Hindley should serve a minimum of 25 years.
Brady was jailed for life with Myra Hindley in 1966 for the murders of five children in Greater Manchester.
BBC: NEWS | UK | England | Manchester | New battle for Brady journalist
In 1966, Hindley and Brady were convicted of murdering two children, 10-year-old Lesley Ann Downey and 17-year-old Edward Evans.
Hindley, now repentant not that that made one jot of difference drew maps for her.
But Hindley, who was jailed in 1966, still intends to challenge the ruling in the House of Lords next month.
Brady was also convicted of the murder of John Kilbride, with Hindley being found guilty of acting as an accessory.
The families also feel they have been given less media coverage than Hindley and her accomplice Ian Brady over the years.
He and Myra Hindley were involved in five child murders between 1963-65.
Instead they should leave Myra Hindley's fate to be decided by judges whose careers are less influenced by the latest blip in the opinion polls.
In 1987, Brady and Hindley confessed to two further murders - those of Pauline Reade and Keith Bennett, whose remains have never been found.
When Myra Hindley, then aged 23, was convicted in 1966, the trial judge made no recommendation as to the length of time she be jailed.
Brady and his girlfriend Hindley lured children and teenagers to their deaths, torturing them before burying their bodies on Saddleworth Moor, Greater Manchester in the 1960s.
His outburst followed Mr Straw's approval of a decision by his predecessor, Michael Howard, that Hindley must serve all of her life sentence and never be released.
In a civilised country like ours we always have cases that cause aversion - for example, the murders committed by Rosemary and Fred West or Myra Hindley.
The veteran penal reform campaigner accused Mr Straw of being swayed by public opinion, which Lord Longford said was being stirred up against Hindley by "wicked" tabloid newspapers.
Hindley, who lost an appeal against a ruling that she must spend her life in jail, has been dubbed "the most evil woman in Britain" by the press.
"She must be one of the longest serving female prisoners in the country apart from Rosemary West and Myra Hindley, and just for three ounces of heroin, " she said.
Lord Longford has expressed his "total disgust" at the Home Secretary Jack Straw's decision to confirm that the Moors Murderer, Myra Hindley, will spend the rest of her life in prison.
Cannon Andrew Hindley from the Cathedral has defended the move - he says it's certainly not a personal reflection on his female colleague, but it is a situation that will be reviewed when the Dean returns from holiday.
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