After completing her D Phil thesis "A unified analysis of discretisation methods" at Oxford in 1984, Jennifer was awarded a Junior Research Fellowship at St. John's College, Oxford. After eighteen months, she left Oxford to take up a position in the Theoretical Physics Department of the National Radiological Protection Board in south Oxfordshire.
In 1987, Jennifer joined the Numerical Analysis Group at the Harwell Laboratory. The Group moved to the Atlas Centre at the Rutherford Appleton Laboratory in 1990. In 2007, she became the Group Leader, a role she continued until 2018 (with the Group changing its name to the Computational Mathematics Group in 2017). In 2011, Jennifer was promoted to be an STFC Individual Merit Research Fellow. Much of her work at STFC and that of the Group has been funded by EPSRC research grants.
In 2016, Jennifer was appointed Professor of Mathematics at the University of Reading and Director at Reading of the EPSRC Centre for Doctoral Training in the Mathematics of Planet Earth. As a result, she now works part time (2 days a week) for STFC and spends the rest of her time at the University of Reading.
Jennifer is a Fellow of the Institute of Mathematics and its Applications (IMA) and was an elected member of the IMA Council (2013--16). She is an elected member of the IFIP Working Group 2.5 on Numerical Software, she served on the Women in Mathematics Committee of the London Mathematical Society (2006--14) and on the SIAM Program Committee (2013--16). She was vice president of SIAM UKIE (2015--17). Jennifer is an Associate Editor of ACM Transactions on Mathematical Software and of SIAM Journal of Scientific Computing.