Professor Davidson, a Fellow of the Royal College of Physicians and the Royal College of Radiologists, has been Senior Consultant Oncologist at Broomfield Hospital, Chelmsford, since June 2000. Prior to that he held a similar position at the North Middlesex Hospital for 10 years. While at the North Middlesex, in 1993 he set up a cancer-research department where he was involved in major trials developing state-of-the-art treatment for cancer patients.

In January of 1999, Professor Davidson (Chairman of Heal Cancer Charity) and his patients, including Helen, set up theHelen Rollason Heal Cancer Charity.

In 2003, Professor Davidson launched the Helen Rollason Research Laboratory in collaboration with APU (Anglia Polytechnic University). As the lab's director of research, he is responsible for developing both quantitative and qualitative research programmes in cancer.

He has also pioneered cancer out-reach work in district general hospitals and established multi-disciplinary clinics locally in partnership with consultant surgeons and physicians.