London Cabbie Knowledge

I'm not so sure. When people follow sat navs they never actually know where they are or where they're going, just when they next need to turn.

When they are dumb. If you know the area, you use the Sat-nav for a convenience only. Especially with live traffic updates.
They obviously can't handle "the Knowledge". You're a shell of a man afterwards. Need to read Daily Star to comprehend the news.