Tracey Newman, chief operating officer at the Charity Commission, has left the regulator for personal reasons after four months in the role.
A spokeswoman for the commission said that Newman, who joined the regulator in April, had made the "difficult decision to resign" for personal reasons and left in early August.
Newman, who was based in the regulator’s Bootle office, joined the commission after three years as director of dispute resolution at the Ombudsman Services, an independent not-for-profit organisation. She previously spent 20 years in operational roles in the mobile telecommunications industry, latterly at O2.
Newman’s appointment was one of the final elements of the regulator’s smaller, five-person senior management team, put in place by Paula Sussex after she became the commission’s chief executive in June last year.
Sussex will lead Newman’s old directorate while a successor is sought, the commission spokeswoman said.
"We are confident that, with the support of the commission's board, directors and staff, we will maintain the momentum of change in our operations directorate, aimed at increasing the commission's efficiency and effectiveness," the spokeswoman said.
She said no further details about Newman’s departure were available.
Advertisements for Newman’s successor would appear over the weekend, the spokeswoman said.