Question

Who was buttoning up his coat in carbuncle

Answer 1

Breckinridge

Breckinridge,” he continued, buttoning up his coat as we came out into the frosty air. “Remember, Watson that though we have so homely a thing as a goose at one end of this chain, we have at the other a man who will certainly get seven years' penal servitude unless we can establish his innocence.