[1] Du Cann served as Treasury counsel (prosecution barrister) for the Inner London quarter sessions from 1966 to 1970 and for the Central Criminal Court from 1970 to 1975 but also worked in defence.
[2][3] Du Cann was also involved in one of the inquests into the 1982 suspicious death of Italian banker Roberto Calvi and the 1992 Blue Arrow fraud trial.
[1] With Geoffrey Robertson he was appointed to defend British MP John Stonehouse in his trial for charges arising from an attempt to fake his own death in 1974.
Du Cann wrote a book aimed at instructing law students, The Art of the Advocate, that was first published in 1964 and in a revised edition in 1993.
From around 1977 Du Cann gave an annual lecture, focussing on professional standards, for the Council of Legal Education.