The leaflet describes the walk as "London Bridge to Southwark", perpetuating the anatopistic* naming of the station at the junction of The Cut and Blackfriars Road. The soi-disant "Southwark" station is a long way from the heart of Southwark itself (the borough that grew up around the south end of London Bridge), for which the closest stations are Borough and London Bridge, and indeed "Southwark" station is partly within the neighbouring borough of Lambeth. The seemingly arbitrary end of the "Low Line" is the borough boundary.
*anatopism - the geographical equivalent of an anachronism