This sub-series contains a large quantity of correspondence and some additional papers generated by MK during the research and writing of The Works of Ralph Vaughan Williams (London: Oxford University Press, 1964). The correspondence largely relates to MK's attempts to track down information on specific works by RVW, such as details of first performances, names of performers, different arrangements, instrumentation, and the whereabouts of scores. It therefore includes letters not only from reference assistants and officials, music experts and scholars, but also from friends of RVW, well-known musicians, composers, conductors and writers, including figures as diverse as Adrian Boult, John Barbirolli, Benjamin Britten, Julius Röntgen, Larry Adler, and Bertrand Russell, amongst others. The correspondence reveals MK's meticulous research into all of RVW's compositions and arrangements, which resulted in the detailed list of works published as the first appendix of his musical biography (as he states in various letters, he intended to write a book containing as much factual detail as possible rather than another 'critical study'). Many of the letters also contain reminiscences and anecdotes about RVW. The largest bundle of letters comes from Ursula Vaughan Williams, the composer's widow and a poet and librettist in her own right, with whom MK collaborated closely in writing his book. Her book, R.V.W. A biography of Ralph Vaughan Williams (London: Oxford University Press, 1964), forms the companion volume to MK's musical biography. She forwarded to MK any letters she considered to be of use and any queries she felt he would be able to answer, as well as supplying much information herself.
The correspondence also illustrates MK's progress with the book, which he began researching in 1960. The typescript was completed in August 1963; it was in proof stage by early 1964 and was published in the autumn.
In addition to the correspondence, there are a number of programmes for performances of works by RVW and various rough notes made by MK during the course of his research.