A deep dive into the history and technical innovations that have facilitated the (usually) speedy transit of millions of daily passengers across London. We begin with a short history of the network, cover the differences required for tunnel based signalling under a bustling capital, explore some amazing inventions to handle rising passenger demand, and finish with the current state of communications based train control which has been gradually displacing traditional fixed signalling on the underground. The author is a volunteer at the London Transport Museum but this talk is not affiliated.