Possible Clues:

• Ketch kitchen
• Dropped writing in passage for the early edition
• Proof of legality? Unfortunately it's missing
• Vessel — or a chamber on it?
• Grand passage provides proof
• Key to passage leading to kitchen
• Brass found on the ancient overturned ship
• Ship providing good passage
• Kitchen garden walk that's good at the start
• Proof of delay when returning with 'Magic Line'