Soon after his wartime experience, in 1949 he delivered the Swarthmore Lecture, and applied his clear thinking and his understanding of Quaker processes to examine how a religious concern can be made manifest in practical work, and what needs to be considered so that this can be organised. 'The true "concern" is a gift from God, a leading of his Spirit which may not be denied.' How is the authority for this held by a human organisation? What kind of people does it need to lead and carry out its work? Subtitled 'A study in motive and administration in Quaker relief work', Authority, Leadership and Concern was soon recognised as an essential book, was reprinted in 1970, and is still valuable in the next century.