Karen Pierce has become the first woman to be appointed as UK ambassador to the United Nations, the most prestigious post since the UN began in 1945.
The political director will take over the role in January, succeeding 18 different male representatives at the UN in New York.
She is a former UK deputy permanent representative, and also represented the UK at the UN and the World Trade Organisation in Geneva.
Pierce will succeed Matthew Rycroft, who is to return to the UK as permanent secretary to the Department for International Development.
Rycroft will replace Mark Lowcock, who has taken up a senior humanitarian co-ordinating role at the UN.
British foreign minister Boris Johnson welcomed the appointment, saying Pierce would add to Britain’s “proud history of working for positive change through the United Nations, not least in addressing the problems in Libya and Syria”.
“I know Karen has the diplomatic skills, energy and patience to continue this vital work, and I congratulate her on her appointment,” he said in his statement.
Pierce has two grown-up children, and is married to Charles Roxburgh, the second permanent secretary at the Treasury.
Promising to be a force for partnership and progress at the UN, Pierce said:
“The UK has long been a strong supporter of the UN and its role at the heart of the global rules-based international system, at a time when it is coming under challenge.
Through our role as a permanent member of the security council and position as the UN’s third-largest donor, the UK will continue to work with others to tackle the pressing security, stability, development and prosperity challenges of today.”