His continued work into carcinogens at the Imperial Cancer Research Centre at the John Radcliffe Hospital, Oxford, working as part of the Clinical Trial Service Unit, notably including a study undertaken with Sir Richard Peto, in which it was estimated that tobacco, along with infections and diet, caused between them three quarters of all cancers, which was the basis of much of the World Health Organization's conclusions on environmental pollution and cancer.
Penelitiannya berlanjut mengenai karsinogen di Pusat Penelitian Kanker Imperial di Rumah Sakit John Radcliffe, Oxford, bekerja sebagai bagian dari Unit Pelayanan Percobaan Klinis, terutama sebuah penelitian bersama Sir Richard Peto yang memperkirakan bahwa tembakau, bersama infeksi dan diet menyebabkan tiga perempat dari semua jenis kanker, menjadi dasar dari sebagian besar kesimpulan Organisasi Kesehatan Dunia mengenai pencemaran lingkungan dan kanker.