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A bit out of date, but this interactive map of step free London is very good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 :
Caledonian Road & Barnsbury is on the London Overground, and is accessible to wheelchair users with lifts to access platforms. Boarding ramps are also available. See pictures and further accessible transport in London detail from links below.
Underground lines : London Overground (North London line)
AccessAble Access Guide :
Accessibility friendly : Yes (TFL).
General description : See wiki
More comment : National Rail Map & Guide . Step-free access to ticket office and footbridge Lifts to island platform. There is a long path sloping up from the ticket office to the footbridge.