When Louise Robert-Smith steps in to take control of the troubled MLC school this month, the situation before her will be a familiar one.

Staff resignations, parent revolt and student unrest had divided another Sydney private girls' school before she first walked through its gates a decade ago.

Ascham, in Sydney's eastern suburbs, had been led by three headmistresses in eight months and gone through a public parent revolt when the now 67-year-old took the helm in 2005.

It had been faced with poor academic results and a parents' vote of no confidence in the school's board.

Mrs Robert-Smith's task was to get the school out of the news.

"That was part of the brief when I came to [Ascham], we didn't want to be a part of the papers, we'd had enough of that. It was a conscious decision that I would keep a low profile," she said in an interview with the University of Sydney in 2012.

A decade on and parents at MLC are hoping for a similar style of leadership as students get ready to go back to the Burwood school in 2016.

The past month has seen the public airing of years of simmering allegations of questionable workplace practices, low morale and teachers being forced to leave.

The school has lost four heads of its middle, junior and senior schools and key members of its world-renowned music department over the past two years, including its film-star music director, Karen Carey.

Tensions came to a head in the lead-up to the school's speech night in December. There were threats of protests after student-led petitions were deleted from websites and disgruntled parents called for principal Denice Scala's sacking and adopted the hashtag #ReclaimOurMLC.

Despite the school returning strong academic results, including its 30th perfect score in the International Baccalaureate this year, the Scottish-born educator resigned on Thursday, just weeks after she promised parents stability in 2016.

Mrs Robert-Smith was immediately appointed her interim successor.

The understated principal had led North Sydney Girls for seven years before taking up the high-profile position at Ascham.

Fluent in Indonesian and French, the former languages teacher believed she could bring stability back to the Ascham, which charges students up to $28,000 a year and has educated generations of Packers.

"I thought I could make a real difference [there]. One of my strengths is building community and building morale," she said in 2012. "Ascham wanted a safe pair of hands, someone who was Sydney-based, knew about Sydney, knew how things ran and who was an experienced head."

She earned the praise of Justice Margaret Stone, Australia's Inspector-General of Intelligence and Security, and former Ascham chair, who told Fairfax Media in 2005 her leadership of North Sydney Girls made her "equally appropriate to her leading a top private girls school".

After successfully stabilising the school, taking it out of the news and back to the top of the rankings, Mrs Robert-Smith left Ascham after eight years in 2013.

A year after her departure, the Edgecliff boarding school lost its internationally recruited principal, Dr Helen Wright, with the school citing "significant differences in approach and style".

While Mrs Robert-Smith prepares to assume her post at MLC on January 21, the school has already begun looking for her replacement. It has launched an international recruitment drive for 2017.

A spokesman for MLC said the school could not contact Mrs Robert-Smith for comment because she is travelling overseas.

The chair of the MLC School council, Pauline Johnston, declined to comment.