Dame Helen Ghosh has announced she will be stepping down as director general of the National Trust in March next year.
Ghosh has led the conservation charity since 2012 and has announced that she will become master of Balliol College at Oxford University in April 2018.
The trust said it would begin the process of looking for a new director general in the autumn.
Tim Parker, the National Trust’s chairman, said Ghosh had done an “outstanding job” as director general.
He said: “She will be leaving the organisation in great shape – one clear of its future direction with ever growing levels of investment in conservation.
“We are indebted to Helen for all she has done and wish her well in her new role.”
'Right time to move on'
Ghosh said: “There is never a good time to leave a job that you love, so the decision was a very tough one. But the trust is in a great place and in great hands, and 2018 which will be my sixth year here seemed the right time to hand over to someone else.
“I am enormously proud of all the trust has achieved over the past five years, with the conservation of nature and heritage at the heart of what we do and an extraordinary growth in membership, support and visits.”