The Japanese, Ooma, must have met Sir Alan and discussed this very question with him.
The baronet must have unwittingly revealed the family secret, and the Jap was clever enough to perceive its value.

Further, the murder was unpremeditated, the inspiration of a desperate moment, and the weapon selected shows a sort of fiendish mandate suggested by family feud.

Ooma is undoubtedly--" But Smith entered, apologetic, doubtful.
"Mr.Holden is here, sir, and says he wishes to see you immediately." Holden's news was important.

Capella had left Liverpool Street half an hour ago for Beechcroft, and in the same train travelled Ooma.
"Are you sure of this ?" demanded Brett, excitedly springing from his chair.
"Quite certain, sir.

Mr.Winter's mate followed him to the station, and told me who the Japanese was.