Humphris is a member of the advisory boards of two Leighton companies and also chairs Leighton’s tender review and risk committee – a significant component of the company’s business transformation strategy.

Humphris has been an independent non-executive director of Leighton Holdings since 2004.

In addition, he is chairman of mining services company Ampcontrol and a director of the Australian Securities Exchange-listed Australian Infrastructure Fund.

Prior to that, he spent 10 years as managing director of Peabody Resources and 23 years in executive positions with a major UK-based construction company.

He also chaired the New South Wales Coal Association.

Humphris referred to Leighton as “one of Australia’s great companies” and said it was a privilege to chair it.

He assured Leighton’s stakeholders that last week’s three shock resignations wouldn’t hamper the company’s strength and strategy going forward.

“Leighton is in a strong position with real momentum,” Humphris said.

“The board, the major shareholder and management are all firmly committed to Leighton and are absolutely focused on managing the business in the best interests of all stakeholders.

“Our immediate priority is to identify and appoint additional independent directors with the capability to contribute to the further development of Leighton.”

Jones and non-executive directors Wayne Osborn and Ian Macfarlane all handed in their resignations last Friday due to their belief that major German shareholder Hochtief was no longer supporting an independent board at Leighton – an accusation Hochtief denied.

“For several decades, Leighton and Hochtief have chosen to follow a set of informal and non-binding governance principles which include a board and management structure in which the majority of directors are not Hochtief-associated directors,” Hochtief wrote in a letter to Leighton Holdings.

“Hochtief has at no time given the Leighton independent directors any cause to believe that it intends to depart from these principles.”

Humphris further stressed Hochtief’s commitment.

“The board are committed to Leighton's strategic objectives and totally support the

[chief executive officer] Mr Hamish Tyrwhitt and his management team,” Humphris said.

Paula Dwyer has been appointed deputy chair.

She will lead a special committee of the board to oversee the appointment process of non-executive directors to replace outgoing Osborn and Macfarlane.