A file of correspondence to and from the Cabinet Secretary Sir Norman Brook during his visits to Canada, Australia and New Zealand, concerning constitutional issues of the Commonwealth. Subjects covered in the file include the ranking of Commonwealth commissioners from different member states, concerns over possible unwillingness to recognise the authority of the British Crown on external affairs, the importance of keeping India in the Commonwealth, and fears in Australia, New Zealand and Canada that allowing some members a looser constitutional association with the Crown could change their own relationship with the UK.