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A bit out of date, but this interactive map of step free London is very good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 :
Edmonton Green is on the London Overground network. Lifts to the platform level became operational in 2015.
See pictures and further accessible transport in London detail from links below.
Underground lines : National Rail Greater Anglia
AccessAble Access Guide :
General description : See wiki
More comment : National Rail map & guide