Possible Clues:

• Notice Edmund deployed rider
• An emu three daughters trained for rider
• A theologian facing ruin, then Greek character backed supplement
• Heads of Durham University in new demand for material to go in book
• Supplementary text tacked on to the end
• Item appended to book
• Another word for appendix, in its literary meaning
• Tripped and mudded extra
• PS: Tipsy dad and mummy regularly hugging, close
• Notice Edmund abused rider