Madeleine was the Prime Minister's Adviser on National Resilience and Security and UK Deputy National Security Adviser. She has been in government service since 1988 working in a number of overseas and UK postings with the Foreign & Commonwealth Office. She was appointed Permanent Secretary for the Northern Ireland Office in January 2020 and still serves in this post.

She was appointed to the post of Chair in November 2019 following nomination by the Cabinet Office and took over with effect from 1st January 2020.