Is retained responsibility a matter for expert psychiatric evidence?

have led to discussion as to whether retained responsibility is a matter for expert psychiatric evidence. The view of the author is that it is. Analysis of the case, sentencing guidelines, and case law are used to support this viewpoint and to demonstrate similarities with the position adopted by Hallett in his influential paper 'To what extent should expert psychiatric witnesses comment on criminal culpability?', published in 2020 in this journal, which critically examined the boundaries of expert psychiatric testimony regarding culpability. Suggestions are made as to how psychiatric experts should respond if asked to assist with retained responsibility.