David started keeping a note book at the end of 1974 initially to assist him in organising his work as the principle structural auditor for the Dunlin A concrete substructure. Initially the note books containing very brief details of events including actions to be taken, facts not to be forgotten, documents received etc. Entries were made as and when necessary and not on a daily basis. Over time a more structured approach was adopted and soon entries were made on a regular basis for most working days. The day books, usually referred to throughout his working life as his "Black Books" (although for a period they were red!), include records of conversations, notes taken at meetings, lists of things to do, pasted-in notes from his secretary, details of travel arrangements and, since 1993, details of his working arrangements in Norway. As well as a record of his professional activities the day books also contain a number of entries relating to personnel matters, particularly church activities. The vast majority of the entries in the day books were made at the time the events occurred and no efforts have been made to provide a summary or commentary on the events. The purpose of the day books was to simply record what factual information not to record events for posterity. The primary reason for recording the minutiae of his working life in a day book has not changed since David first started in 1974. The purpose, he says, is "to assist me in effectively organising my work and to provide me with a record of actions, conversations and meetings that might be helpful to me in the future".