Typically period pieces rely on their wardrobe department to create an item or large costumiers to provide an item. Once costumier Angels in the UK was involved in the Sherlock Holmes production and they may have been a source for Jude Law's coat in the movie. Our shoppers also found some options that you may also find inspiring.
The jacket is very poor variation of a 4th Hussars Officers Frock Coat.
The Original has a lot more detail than in the film.
I make them in all sizes.
Send me your email address, and I'll send you some photos.