Georgia O'Keeffe

1 week ago | dailymail.co.uk | Harry Howard |Georgia O'Keeffe

In central London, just off the bustle of High Holborn, there is a nondescript blue door. Commuters who walk past it on their way to Chancery Lane station will note the bright red and yellow signs adorned to it. The warning that 'trespassers will be prosecuted' is perhaps the giveaway that this is not your typical storeroom or building entrance. Instead, as MailOnline's exclusive pictures and video reveal, it is the gateway to a network of tunnels with a fascinating history.