What does Holmes come to know from the ciphered text?

From the text:

"When you search a single column for words with which to express your meaning, you can hardly expect to get everything you want. You are bound to leave something to the intelligence of your correspondent. The purport is perfectly clear. Some deviltry is intended against one Douglas, whoever he may be, residing as stated, a rich country gentleman. He is sure—'confidence' was as near as he could get to 'confident'—that it is pressing. There is our result—and a very workmanlike little bit of analysis it was!"