Don't agree, McGrath. 'Subway', in London, means an underground passage to cross a road ~~ sometimes in connection with two entrances to an Underground, or Tube, station, sometimes independently provided. The term Subway, for the rail system, while not unknown, I do not think is much used by Londoners themselves. "Will you go by bus or tube [or Underground]?" a Londoner would ask; not "bus or subway?"

~Michael~