‘Prof Willmer: Entertaining Special Guests and Honorary Members’. File contains correspondence and papers concerning special guests at the sesquicentenary celebrations, including honorary graduands of Cambridge University and others who were entertained as guests of the Society during 1969. Includes a list of honorary graduands: Prof Henri Paul Cartan; Prof M[ichael] Polanyi; Prof Sir Vincent Wigglesworth; Prof Harrison Scott Brown; Prof Sir W Lawrence Bragg; Dame Honor Fell; and Prof R N Robertson.