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A bit out of date, but this interactive map of step free London is very good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 :
London Overground (Gospel Oak to Barking)
AccessAble Access Guide :
Accessibility friendly : Partial.
General description : See wiki
More comment : National Rail Map & Guide Step-free access from station entrance to both platforms via a ramp with gradient, but not between platforms (TFL)