I've just come across this 2009 paper by archaeologist Emma Dwyer, with a focus on the railway arches at Pedley Street and Grimsby Street:
'Underneath the Arches: The Afterlife of a Railway Viaduct'
The Great Eastern Railway Company’s viaduct in East London was one of the earliest, and most substantial, railway structures in London, transporting huge quantities of goods and people entering and leaving central London. Rather than considering the official use of the viaduct, however, this chapter will focus on the unofficial, parallel uses of the spaces underneath the arches, long used as a sanctuary and shelter, a series of secluded places where independent businesses and illicit activities thrived.
full text available at: