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A bit out of date, but this interactive map of step free London is very good
All the London railway stations :
Belvedere is on the South Eastern rail network, and is described as entirely step-free to platforms. Boarding ramps are available on the platforms. Entrance to platforms is via side entrances, and to change platforms it is necessary to exit the station. Platform 2 appears to be served by a ramp with a steep gradient. See pictures and further accessible transport detail from links below.
National Rail : National Rail South Eastern
AccessAble Access Guide :
Accessibility friendly : Yes. Step free, partly with the aid of ramps.
General description : See wiki
More comment : National Rail
Map & Guide
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