Dame Lowell Goddard, the former New Zealand judge heading the Government's child sex abuse inquiry, could receive more than £5 million (NZ$9.17m) in pay and perks amid fears hearings will drag on for a decade, The Telegraph can disclose.
Dame Lowell's remuneration package, which includes numerous free flights home and a £110,000 a year rental allowance, has catapulted her to the top of the public servants' paylist.
Campaigners described the flight and accommodation allowances as "highly questionable".
Dame Lowell earns a basic salary of £360,000 a year. But that is topped up with the rental allowance, an additional £12,000 a year for utilities bills and a car and driver for official business - all paid for by the Home Office.
The four free return business class flights to New Zealand every year for her and her husband is a further perk reckoned to be worth £40,000 annually.
Business class return flights to new Zealand typically cost £5,000.
On top of that her immediate family - thought to be the couple's four children - are each entitled at British taxpayers expense to two return flights each between the UK and New Zealand. The value of those flights is about £15,000.
The huge sums will cause alarm amid concern that the Independent Inquiry into Child Sex Abuse (IICSA), set up in March 2015 by the then Home Secretary Theresa May, is already behind schedule.
No public hearings are now expected until March next year "at the earliest" with one lawyer, representing a number of child abuse victims, suggesting the inquiry could easily last ten years.
If it does drag on that long, Dame Lowell's remuneration package will easily have exceeded £5 million. The flights for herself and family will have cost the Home Office in the region of £550,000.
Dame Lowell has said "her sincere hope and expectation is that it will be possible to conclude the inquiry's work before the end of 2020".
But the first public hearings due to start in September into claims Lord Janner of Braunstone, who died in December last year, sexually abused children and that his crimes were covered up has been postponed until march next year at the earliest.
Public hearings into two other strands of the inquiry - into abuse within the Anglican and Catholic churches - are not likely to begin any sooner than the second half of next year.
It means that it will have taken two years for the Independent Inquiry into Child Sex Abuse, established by the then Home Secretary Theresa May in March 2015, to hold substantial public hearings into any of 13 separate strands it is currently investigating.
Dame Lowell was presumably in a decent bargaining position to negotiate her pay package when the Home Office invited her to become the inquiry's chair. The two previous choices - Baroness Butler-Sloss and Dame Fiona Woolf - were forced to quit within short succession after campaigners complained they were too close to some of the people who would allegedly be dragged into the inquiry.
Dame Lowell is thought to have earned £180,000 a year in her previous job as a High Court judge in New Zealand.
Her current salary dwarfs the pay of other high profile inquiry chairs.
Sir John Chilcot, who headed Iraq Inquiry, was paid a day rate of £790 - equating to £205,400 a year - while Sir Brian Leveson who chaired the inquiry into Press standards and ethics took his normal £197,000 judge's annual salary.
She is also paid substantially more than the highest-paid judge in England and Wales, Lord Thomas of Cwmgiedd, the Lord Chief Justice, who receives just under £250,000 and almost twice the salary of Simon Stevens, chief executive of NHS England.
Harry Davis, campaign manager at the TaxPayers' Alliance said: "Justice Goddard is presiding over a serious and sensitive inquiry, but the financial deal handed to her will rankle with many taxpayers.
"Given that she is being paid an extremely high salary, her generous 'living allowance' and international flights home are highly questionable." he added: "The authorities owe it to taxpayers to keep the costs of these arrangements under control, especially when the inquiry over which she is presiding could last for a number of years."
The Taxpayers' Alliance said by its reckoning only two public servants - both involved in the HS2 high speed rail link - earned more.
Some lawyers have privately expressed concern about the delays and the handling of the inquiry by Dame Lowell. In one exchange during preliminary hearings last week, she admitted she was unsure of 'local law' - meaning English law - when police tried to block some details of an investigation being made public.
A spokeswoman for the Inquiry said: " The Inquiry is committed to completing its work as quickly and cost effectively as possible while remaining thorough.
"It will publish reports on investigations as they are completed during the course of the Inquiry, not wait until the conclusion of the full Inquiry.
"It will also publish an interim report in 2018 (as it is required by its terms of reference to do) and annual reports to reflect progress to date and work going forward."
Goddard inquiry - In numbers
£17.9m 2015/2016 budget
155 Staff members hired to date
£360,000 Dame Justice Goddard's annual salary
33 Alleged victims of Lord Janner
188 Core participants in the inquiry
13 Separate historic abuse investigations carried out by the inquiry
2,000 Alleged child sex abuse victims who have contacted the inquiry
From: Auckland, New Zealand.
Family: Married to Christopher John Hodson QC and has three step-children and one daughter from her first marriage.
Education: Law at the University of Auckland.
Current job: Head of the UK Government's child sex abuse inquiry.
Experience: Started work as a barrister in 1977 and then became Judge of the High Court of New Zealand from 1995.
She was the first woman of Maori descent to be appointed. She was one of the first women to be appointed Queen's Counsel in 1998 and became Deputy Solicitor-General for New Zealand in 1992.
In 2007, she chaired a year-long inquiry into police handling of child abuse investigations in New Zealand. She is also a UN committee member who has experience of working with victims of sexual assault and has helped establish a new clinic for survivors of sex abuse.
The Goddard Inquiry
Opened: July 2015
Duration: Up to five years
Led by: Justice Lowell Goddard - a senior New Zealand judge
Remit: To investigate whether institutions and organisations have taken seriously their duty of care to protect children from sexual abuse in England and Wales. These include:
• local authorities
• the police
• the Crown Prosecution Service
• the Immigration Service
• the BBC
• the armed forces
• children's homes
• churches, mosques and other religious organisations
• charities and voluntary organisations.
"The sexual abuse of children over successive generations has left permanent scars not only on successive generations, has left permanent scars not only on victims themselves, but on society as a whole."
- Dame Lowell Goddard