Wow, if confirmed this would be great news! andrewr, have you any further information on this?

The Northern Line at London bridge has nice platform ramps to allow level access to the carriages. They seem to be modular bolt-on components with a ramp and then a level area next to where the doors are when the trains stop. However, since Honor Oak Park has various types of train that stop in different places, I am not sure whether this type of part-raised platform could work? The raised areas might not always correspond to the location of the carriage doors.