What you see in Regent Street now is a 1910 rebuild of the Nash from 1810. Along the edges of Regent’s Park, you have these big, long terraces designed like palaces, so the wealthy people in the row houses could feel like they were living in a wing of Versailles. Then, behind that, there are tiny curving streets with modest houses for those days, which were intended for middle-class people.
Funny to think of multi-family that way. But a good way to think about it...as residence in someplace beautiful, with a unified sense of design. Not a whole city built in one design style, but a community with a unified esthetic, rather than one of ticky-tacky takes on 'romanesque' and 'cottage' on an ad hoc basis. Part of the reasons suburbia needs such wide distances between houses is that the styles are so clashing.