Mens Victorian Vest and waitcoats
A men's frock coat with black trousers. He is also wearing a black shirt with brass buttons in the middle. The tips of the sleeves are white, so he is probably wearing a tunic or undershirt.
Sweeney Todd's vest style, middle vest second row from bottom, collar style and double-breast places the costume in the
Victorian Upper-Class Men and their Daily Lifestyle - Art of Manliness
Suits change for a rich man. While not as elaborate or ornate as the female counter parts, men at Rochester's party certainly would have brought a sizable trunk of clothes.
Victorian Men’s Costume, Dickens Fair Costume,