Networkx Read Ordnance Survey - Itn Integrated Transport Network?/reading Gml File

I met some problems. I want to import ordnance survey - ITN Integrated Transport Network into networkx to do some network analysis. Since the ITN is in a GML 2.1.2 format, I tried

Solution 1:

It looks like the GML you are citing is the Geography Markup Language https://en.wikipedia.org/wiki/Geography_Markup_Language and the GML referred to in NetworkX is the Graph Modeling Language https://en.wikipedia.org/wiki/Graph_Modelling_Language.