Complex sentence: In 1947 he was invited by Glyndebourne to be Assistant Producer to his father whose first post-war Glyndebourne production was "Orfeo" by Gluck, with Kathleen Ferrier.
Split into simpler sentences: In 1947 he was invited by Glyndebourne to be Assistant Producer to his father. This was Carl Ebert's first post-war Glyndebourne production, "Orfeo" by Gluck, with Kathleen Ferrier.