Possible Clues:

• Surprised to be awake?
• Old Swan looked astonished
• Astonished; fully aware
• Sounds as if I'd follow round the writer when not asleep
• Alert writer easily loses heart dipping into dictionary
• Vigilant round sty I'd say
• Amazed to be so alert?
• Frank, I'd heard, is aware of what's involved
• Surprised - aware
• Forming an encrusted mass