And would this mean that IF the lean-to was added later, then so was the arch extension that hovers over Mary's door? And IF these were added after the main house then what about the court cottages seeing as the left cottages are a continuation of the extra archway that is above the back window to 27's shop?
Those two windows (red/yellow arrowed) are curious indeed! Especially the one obscured by the lean-to roof.
Miller's Court was originally a garden wasn't it?
I have a plan of a similar set of cottages built off Opal Street, Kennington. Originally a garden; a court of 'one up, one down' cottages was built there. The floor plans of the original cottages even look exactly the same as the floor plans of the houses in Miller's Court. Mark Ripper found and posted a plan of the layout of the cottage/house close to 13 Miller's Court where Kitty Roman was murdered/