Stay away from that 1830 frock coat pattern. its the worst piece of drek Ive ever bought. None of the parts line up correctly. I ended up junking it totally and drafting my own using The Costumer's Manifesto: The Cutter's Practical Guide 1893-1898 by W. D. F. Vincent as a guide.
Finding this info took incredible investigative skill, lol I am seriously impressed. so much in fact, that I have been in touch with Belstaff Flagship Store in Manchester, UK. If you are interested in one of these, they are limited...i think out of production. Their last message to me:It is a Belstaff Millford coat and it available at their stores as of now, but they are a bit pricy. I would have liked one till I found out that it costs 1350.00 pounds - that is over $2100.00 US dollars. I like it, but not that much
Personally I would just find a very cool vintage coat. I find that vintage coats are more distinctive and unique. You may even be able to find something very close to Sherlock's coat for a fraction of the price.