Two collections donated by Simon Keynes and Sir Geoffrey Keynes have been combined to form this series. It has been noted at file and item level who the donor is. The series, sub-series, and sub-sub-series divisions are artificial creations during cataloguing but the file level organisation of items into envelopes was pre-existing. The original order of items within envelopes has been maintained throughout. The Sub-sub-series titled Correspondence to George H. Darwin and Lady Margaret Keynes' Research have been combined and reorganised at the file level to be in chronological order based on the earliest date. The rest of the sub-series and sub-sub-series maintain the relative order of files. The two collections have been distinguished: those donated by Simon Keynes are catalogued in the section before donations from Sir Geoffrey Keynes.