Here is one frame of the footage that I discovered at the AP Archives that had no sound — 5 minutes of film taken at the mass burial of 81 children and one adult on October 27, 1966.
“Loving Shepherd of Thy Sheep” was sung at the service on the hillside. Here is a short demo excerpt from Aberfan, Final Hymn:
My composition Aberfan (7 pianos, voice and tools of rescue) is a sponsored project of New York Foundation for the Arts (NYFA), a 501(c)(3), tax-exempt organization. Contributions on behalf of Aberfan must be made payable to NYFA, and are tax-deductible to the extent allowed by law.
Laura Siersema 
Beautifully haunting music, perfectly summing up what happened
Dear Kellie — thank you very much — I have been so aware, throughout the process of composing “Aberfan”, that it carry the events themselves, that it be true; it is a following of an intuition, a necessity to create sound of everything that happened — Laura