He was formerly acting National Security Adviser, having taken over the role while David Frost continued as the United Kingdom's Chief Negotiator to the European Union during the Brexit negotiations.

[4] Quarrey, who joined the Foreign and Commonwealth Office in 1994,[5][6] previously directed its Near East and North Africa Department.

He has also served as a British diplomat in Harare, in Delhi and at the United Nations in New York.

When Tony Blair was British prime minister, he was his private secretary for two years.

[12] In 2021, he tested positive for the Indian variant of COVID-19 after returning from a government business trip to India.