To my eyes, this man bears a resemblance to the author H Rider Haggard, whose family I’ve already referred to in my previous posts (see here and here). The National Portrait Gallery website has some great images of the author, though he is older in most of them. This one, for instance:
On close inspection, the noses are different. And I’ve yet to come across a photograph of Henry Rider Haggard sporting such a large beard. So I’m inclined towards the theory that the man on the carte-de-visite was an older brother, either Alfred Hinuber Haggard, Bazett Michael Haggard or William Henry Doveton Haggard, who would all have been in their twenties when the photograph was taken.