Dame Fiona Reynolds, the director-general of the National Trust for the past 11 years, is to step down from her post to become Master of Emmanuel College, Cambridge.
During her time in office, she has seen membership of Europe's biggest conservation group grow from 2.7 million to more than four million. Visitor numbers to the trust's 300 properties have risen to 19 million from 10 million a decade ago. She has also added to the 617,000 acres of countryside under the trust's care.
Since last summer, Dame Fiona has been the outspoken leader of the fight against the Government's controversial planning reforms, which campaign groups fear could give the green light to inappropriate urban sprawl and development in rural areas.
The 53-year-old will leave in the autumn of 2013 to be the first female Master of Emmanuel. She said: "I have loved every minute of leading the National Trust and working with our passionate and dedicated staff, volunteers and supporters. And, as a Cambridge graduate, I am thrilled to be going back to head one of its finest colleges."