This series contains correspondence and a small number of other papers relating primarily to the research, writing and publication of MK's books on Ralph Vaughan Williams and Edward Elgar. It includes letters from family members (Vaughan Williams's widow, Ursula, and Elgar's daughter, Carice Elgar Blake), and in the case of Vaughan Williams, additional letters from various well-known figures in the world of music, diverse writers, scholars, friends and acquaintances. Sometimes copies of MK's letters survive, thus preserving both sides of the correspondence.
The series has been divided into 3 sub-series, the first two containing correspondence relating to Vaughan Williams and Elgar respectively, and the third containing two miscellaneous items which do not obviously belong with the rest of the material.