Mikey suggests that Colebrooke Road covers the Regents Canal
Here’s the pictures from the wall near my bathroom (1835 on the left)
It seems to me that looking at the roads around, nothing has changed their alignment – Upper Street, Essex Road (described in 1835 as Lower Road), Pentonville Road and City Road. Colebrooke Road follws the path perfectly – it even joins up with Upper Street at the right place, and you see Regents Canal goes into tunnel just short of it.