The Guardian’s local boss is departing just months after the company appointed a new editor for its Australian edition.

Managing director Rebecca Costello will leave the Australian outpost of one of the United Kingdom’s largest newspapers on September 18, after three years in the role.

The Guardian appointed David Munk as its Australian editor in June, following the sudden exit of his predecessor, Lenore Taylor, four months earlier.

Taylor’s departure came as a shock to staff, but followed several months of tension between her and Costello, who had been managing director since 2023.

On Monday, Costello said she was proud of what The Guardian had accomplished under her leadership.

“I’ve spent much of my career in journalism because I believe deeply in its value,” she said in a statement issued via the publication. “Quality, independent journalism plays an essential role in a healthy democracy, and it has been a privilege to lead the Australian business of an organisation built around that purpose.”

The publication said Costello would take some time before taking another job.

Munk is a veteran of the publication who had been a deputy to Taylor in Australia and senior managing editor of the outlet in London before claiming the top editorial job in Australia.

This masthead reported in February that the relationship between Costello and Taylor, the two most senior Guardian employees in Australia, had deteriorated beyond typical tension between editorial and commercial departments.

Costello joined from independent publishing company Schwartz Media in 2023, where she was chief executive. The Guardian’s Australian business posted profits of more than $2 million in the year ending March 31, according to new filings this month.

A statement from global Guardian chief executive Anna Bateson said Costello was leaving The Guardian a stronger business well-equipped to meet “future opportunities”.

“Rebecca has been an excellent managing director of Guardian Australia, working closely with our editors, and leading our commercial teams to succeed through a period of major industry change and digital disruption,” Bateson said. “I have greatly valued her partnership, and wish her well in her future career.”

Costello was approached for further comment.

Costello’s time at Guardian Australia has been defined by editorial overhaul. Alongside Taylor, there has been significant change to its newsroom, including the departure of long-serving political editor Katharine Murphy and then major turmoil in the publication’s Canberra bureau.

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Calum Jaspan is a media writer for The Sydney Morning Herald and The Age, based in Melbourne. Reach him securely on Signal @calumjaspan.10Connect via X or email.