The boundary (East of London Road) is the Anglo-Saxon border between Surrey and Kent. It was the Post Office, long before the days of SE22/SE23 and before the railway, who drew the line down the centre of Wood Lane (now Wood Vale) to separate the Forest Hill and Dulwich (not then a separate East Dulwich) postal districts. The administrative boundary shifted to the postal boundary after Boundary Commission revisions at the end of the 19th century. This was a leisurely process. I don't know the date of the Order In Council that transfered land for Camberwell to Lewisham. I have it in mind that the legal transfer was as late as 1906, but that requires verification. John K