Tim Dunn and Siddy Holloway explore the labyrinthine Camden Town station, and the forgotten wartime shelter built beneath. Plus, Siddy visits a station which hides a lost river.

Tim Dunn and Siddy Holloway explore the disused areas of South Kensington station, with platforms reclaimed by nature and wartime uses. Siddy also heads to Marylebone to reveal the original features on the platforms and the tube infrastructure hidden within the walls of a hotel.

Tim and Siddy are heading to a station you won’t find on modern-day tube maps – Dover Street, now known as Green Park. During the Second World War the abandoned passageways and lift shafts of the original station had an incredible second life as the base for the London Passenger Transport Board whose work kept London’s transport moving against all odds. Next, Siddy delves into the abandoned corridors and platforms of Down Street, closed to the public in 1932, and the scene of some of the most pivotal decisions of World War II.

Tim and Siddy embark on a night-time track walk to the abandoned station of British Museum. The pair discover 1930s hand-painted adverts and white tiling. During the second world war it served as a shelter and spine-tingling clues to the children who stayed there during The Blitz can still be seen. Siddy also visits the houses of Leinster Gardens.

New. Tube fans would be right in thinking there are 272 Underground stations, but Siddy Holloway has such unique access, she is taking Tim Dunn to the 273rd - West Ashfield.

Tim Dunn and Siddy Holloway are exploring a station in the beating heart of London's theatreland - Leicester Square.

Tim Dunn and Siddy Holloway head to the sprawling Heathrow Airport underground stations - the first ever underground rail link between an airport and a city

Tim Dunn and Siddy Holloway discover the hidden corners of Shepherd's Bush.

Tim Dunn and Siddy Holloway snoop around TFL's gargantuan maintenance facility - Acton Works

Tim Dunn and Siddy Holloway explore hidden parts of Archway. Once called Highgate to encourage more people to travel there before an actual Highgate station existed.