Bonus Secrets Of The Underground

Geoff's back on the tube, in a bonus video from our Secrets of the Underground series. Join him as he discovers more old, secret and generally fascinating things about the tube that you probably missed while on your travels. Also, if you've clicked on this info box and are reading this part then WELL DONE! Not everyone sees it. So write in "Bonus Secrets!" in the comments, and it'll confuse everyone else ...