The whistleblower who first brought the case of a young woman with intellectual disabilities known as 'Grace' to the Public Accounts Committee has asked to appear at the committee in person for the first time to challenge evidence given by the Health Service Executive.

The employee of the organisation which cares for 'Grace', made her request in a letter seen by RTÉ's This Week.

PAC chairperson Seán Fleming confirmed that he would view the request favourably when the committee reconvenes.

'Grace' was left in the care of a foster family for 20 years despite physical abuse, gross neglect and possible sexual abuse.

The whistleblower also revealed that a draft report commissioned by the HSE from Deloitte supported the High Court ruling that the organisation caring for Grace had been underfunded by around €600,000 for her care between 2009 and the present.

The letter to the PAC from the whistleblower's solicitor highlights concerns over the funding of her organisation by the HSE; procurement of reports into 'Grace's' care; contacts with gardaí over the publication of those reports; the accuracy of HSE evidence on professionals who made key decisions in 'Grace's' care and how the whistleblower's concerns were treated and investigated by the HSE.

The letter claims that HSE evidence "had fallen far short" of what might have been expected by the committee and the whistleblower "urgently seeks an opportunity to address certain matters raised in the [HSE] testimony during their evidence to the PAC in March 2017".

The whistleblower told This Week that she is requesting to appear prior to the HSE's next appearance before the PAC in late May.

She said: "I'm of the view that if the Public Accounts Committee were to hear evidence from me at this stage, any subsequent appearance by the HSE before that committee should, perhaps, be more productive".

The HSE's next appearance before the PAC is to clarify a number of issues raised by committee members with the HSE in March 2017.

At the March meeting, the HSE corrected evidence given in February 2016 at a specially convened meeting, held to correct earlier HSE evidence given the previous year.

A number of the issues the whistleblower raises are, the letter says, outside the scope of the Farrelly Commission, which is looking into the failings in 'Grace's' care and allegations of a cover-up, amongst other issues.

The High Court ruled last Thursday that the whistleblower's organisation had been underfunded for providing care for Grace by €600,000 between 2009 and the present.

Speaking on This Week, she said that the HSE should apologise to the organisation, its employees and people who used its services for the difficulties caused by the underfunding.

However, in relation to an apology which she had sought over her treatment as a whistleblower, she believed that the HSE's failure to issue an apology to her, which she requested in February 2016, meant that "that ship has sailed at this stage, there is no meaningful apology that can be offered".

The HSE declined to issue a statement to This Week on the issues raised in the letter.

Grace's story was first brought to public attention by the RTÉ Investigations Unit report Duty of Care.