Many thanks to the “Lost Effra” project and the London Wildlife Trust for these maps showing the approximate route of the River Effra.
Course of the Effra map – Dulwich Society
Old Dulwich map showing Effra route
London Map (undated) showing Thames and River Effra before houses.

More information from local Effra expert, Martin Knight: The Story of the River Effra in Dulwich
Map showing approximate culverted Effra route