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A bit out of date, but this interactive map of step free London is very good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 :
Underground lines : National Rail, Bakerloo, National Rail Chiltern Railways
AccessAble :
Accessibility friendly : The British Rail station is accessible, but not the Underground line.
General description : National rail Map and guide. See wiki
More comment : Flat access to all six National Rail platforms, where boarding ramps are available (24 hour advance notice recommended). The Bakerloo underground is not classified as step free; with stairs and escalators between street level and platforms.