“Of course I am,” he retorted. “I thought you guessed that directly you saw Paul when we were up in that recess watching my father put on his disguise. The relationship seemed so evident that I did not feel there was any necessity to explain it.”

“But you call yourself Casteno?”

“No; I changed my name after I had quarrelled with my father some years ago and got employment in the Royal Household of Spain. I purchased the right to do so—”

“Then you talk English like a native.”

“So does the hunchback.”

“And when that morning you saw your brother,” I went on, breaking away on a new tack, “why did you go after him?”

“To make peace if I could. As it was doubtful I prepared myself also for war.”

“And did you find him?”

“No; he was too quick for me. I slipped as hard as I could to his chambers in Embankment Mansions in Whitehall Court, but he was not in them. They were closed and locked.”

“Embankment Mansions in Whitehall Court,” I repeated. “That is where Colonel Napier lives.” And as I uttered the name of the dead officer I scrutinised every line on Casteno’s face.