Kenneth MacMillan created the one-act ballet Cain and Abel/Kain und Abel for the Deutshe Oper Ballet which premiered on 1 Nov 1968 at the Opera House, Berlin. The material comprises:

1. Typed letter from Miss R Ampenoff, Director of Boosey and Hawkes, Music Publishers, to Kenneth MacMillan at the Deutsche Oper, Berlin, confirming that the full score and orchestral material of Sinfonia Sacra will be ready to send to Germany. The composer, Andrzej Panufnik, has asked for further details of the ballet. 17 Sep 1968
2. Typed letter from David S Adams, Managing Director of Boosey and Hawkes, congratulating Kenneth MacMillan on 'the excellent choreographed treatment of Panufnik's works'. 4 Nov 1968
3. Typed letter from R.Ampenoff at Boosey and Hawked, congratulating Kenneth MacMillan on the great success of his new ballet.
4. Handwritten letter from Andrzej Panufnik to Kenneth MacMillan confirming how much he enjoyed the ballet, even though MacMillan's conception of his score is so different to his. He is delighted that MacMillan would like to work with him on something new, 5 Nov 1968
5. Handwritten letter from Camilla Panufnik to Kenneth MacMillan, looking forward to hearing news of Kain & Abel. Describing how busy her husband, Andrzej, is and how he looks forward to working with MacMillan again, 19 Dec 1968, with envelope