If you want to get to know an area, perhaps before proposing changes, it is always worth visiting. As such, I recently visited the Lewisham area.
Lewisham station has four platforms. Platforms 1 and 2 serve the line to Hayes and Hither Green:
Platforms 3 and 4 serve the line to Blackheath:
The definining feature of the station is the flat junction on the London side of the platforms. The junction provides access to Victoria on the left and London Bridge on the right. There is also access to the south side of the main-line to London Bridge from the Victoria route. This junction is a huge constraint to the local rail network, with trains waiting to cross it. (Trains from platform 1/2 are behind me on the left, and from platforms 3/4 behind me on the right):
Finally, the DLR station has been built beneath the main-line station, providing a connection to Greenwich and Docklands.
In a wet rush hour, the trains were fairly full, and occasionally very full, but perhaps a little less busy than those in the South West. The main surprise was the number of travellers taking trains towards Peckham Rye and Victoria, which was many more than I expected. It was also very, very clear as to just how constraining the flat diamond junction is - there was almost always a train waiting to cross it.