The location is "Back Charlotte Lane", not "Charlotte Lane" - "Back" is part of the name of this narrow thoroughfare. The lane is presumably so called because it runs behind (parallel with) the nearby Charlotte Street. Confusingly though, while the official address recognised by Royal Mail for postal purposes is "Back Charlotte Lane", SIC refers to it (in correspondence and on the sign where it joins Commercial Street) as "Back Charlotte Street". But the lane is far too narrow to be legitimately described as a street!