Shawcross worked on Boris Johnson's mayoral campaign,[4] and became a member of the Council of Economic Advisers to the then-shadow Chancellor George Osborne from 2008, and served for 6 years as his deputy chief of staff when Osborne became Chancellor of the Exchequer.[5] After 2016, she served as chief of staff at the Department for Work and Pensions and was subsequently made a non-executive director for 2020–2022.[3]