And, of course, the endless tramp of hurrying feet. Of shoppers, commuters, tourists, businessmen, and media types, always in a hurry to be somewhere else. London hasn't quite reached saturation point yet, like Tokyo, where they have to employ people to forcibly squeeze the last few travellers into a carriage, so the doors will close; but we're getting there.

Joanna stuck close to me as I led the way through the tunnels. It was clear she didn't care for her surroundings, or the crowds. No doubt she was used to better things, like stretch limousines with a uniformed chauffeur and chilled champagne always at the ready. I tried not to smile as I led her through the crush of the crowds. Turned out she didn't carry change on her, so I ended up having to pay for tickets for both of us. I even had to show her how to work the machines with her ticket.

The escalators were all working for once, and we made our way deeper into the system. I took turnings at random, trusting to my old instincts to guide me,

until finally I spotted the sign I was looking for. It was written in a language only those in the know would even recognise, let alone understand. Enochian, in case you're interested. An artificial language, created long ago for mortals to talk with angels, though I only ever met one person who knew how to pronounce it correctly. I grabbed Joanna by the arm and hustled her into the side tunnel underneath the sign. She jerked her arm free angrily, but allowed me to urge her through the door marked Maintenance. Her protests stopped abruptly as she found herself in what appeared to be a closet, half-full of scarecrows in British Rail uniforms. Don't ask. I pulled the door shut behind us, and there was a blessed moment of peace as the door separated us from the roar of the crowds. There was a phone on the wall. I picked it up. There was no dialling tone. I spoke a single word into the receiver.