AbstractThe second world war was a period of intense co-operation between the countries of the Commonwealth on many subjects, amongst which the application of science was important. The value of this co-operation was so obvious that it suggested, even in the darkest days of the war, that arrangements should be made for its continuation when peace came. The early history of this movement has never been fully written up and is almost forgotten. The present writer, then a young catalyst for Commonwealth co-operation gives a personal account of the situation.