Search london history from Roman times to modern day
A bit out of date, but this interactive map of step free London is very good
All the London railway stations :
National Rail : ThamesLink
Accessibility friendly : Step-free access to Ticket Office and Platform 1 (to London) via main entrance. Step-free access to Platform 2 (to Sutton) via main entrance to Platform 2 (to the rear of Lidl car park off Beddington Gardens). Interchange between platforms is via subway with steps, which is not accessible friendly.
General description : See wiki
More comment : National Rail Map & Guide.