She completed her PhD thesis, supervised by Professor Gordon Plotkin FRS at Edinburgh in 1992. She moved to Cambridge in 1998 on an EPSRC Advanced Fellowship, hosted by Professor Robin Milner FRS. She obtained a lectureship at Imperial in 2001, and became professor in 2009. She held a Microsoft Research Cambridge/Royal Academy of Engineering Senior Fellowship from 2005 to 2010 at Imperial.
Philippa directs the Research Institute on Verified Trustworthy Software Systems (VeTSS), funded by EPSRC, from 2017 to 2022. She also chairs the BCS awards committee, which decides the Lovelace medal (senior) and Roger Needham award (mid-career) for computer science and engineering.