'Tell me, Holmes,' said Watson when they were alone again, 'why is it important that Mr Oldacre wrote his will on the train?'
Holmes lit a cigarette. 'Because it means he wrote it yesterday on his journey to see Mr McFarlane. I think it's very strange that he worked on these imporant papers on the train. Perhaps they weren't so important for him.'
'What are you thinking, Holmes?' asked Watson.
'I'm not yet sure what has happened here, Watson,' Holmes replied, 'but give me time, give me time. Now I must leave you and go to Blackheath. I need, I think, to speak to Mr McFarlane's mother and father.'
Holmes put on his coat. 'While I am out, Watson, ask yourself this question. Is Mr McFarlane a stupid man? I think not. But does a clever man immediately kill someone who has just promised to leave him everything in his will?' Holmes gave Watson a long look. 'Goodbye, Watson. Until later.'