From the Economist:
The Economist's new audio guide, which you can hear on our website, takes travellers through the pitfalls of London life by explaining the right etiquette both for meetings and for pubs, and showing how to earn the approval of British counterparts. Hold off on the wine at lunch, shop for souvenirs at Fortnum & Mason, and if you do have to use Heathrow airport, consider taking the Underground. If you're delayed, you'll be able to curse the transport like any good Londoner.
Of course, I would like to have seen this before returning from London...