Sentence:  Because of the transfer of some multiple-units to the Great Eastern line to make good the latter's deficiency in North-East London since the troubles with G.E.C. electrical equipment, a number of local services on the Manchester-Crewe line have lately been worked with locomotive-hauled <WSD>non-corridor</WSD> stock of G.E. Line origin. 
Meaning of the word marked with <WSD> tags:  Of a train or railway coach, not having a corridor running the length of the coach providing access to the passenger compartments; each compartment would have an outside door on each side.