Secrets of the London Underground

Tim Dunn and Siddy Holloway explore the abandoned branch line between Holborn and Aldwych. And at Holloway Road they find out about the Tube's only spiral escalator.

Tim Dunn and Siddy Holloway visit North End under Hampstead Heath. Abandoned before completion, the station became a Cold War bunker.

tim and Siddy explore the disused parts of Piccadilly Circus. Widely regarded as being at the heart of the capital, this station has always been the flagship of the London Underground. It’s grand, it’s opulent, it’s art deco. But it wasn’t always this big. A major expansion in the 1930s involved extraordinary feats of engineering to ensure the tube continued running and the traffic on the busy road junction above wasn’t disrupted.

Tim and Siddy explore the hidden parts of Euston underground station - and there’s a lot to see, including some features not found anywhere else on the London Underground. The tunnels were abandoned in the 1960s and this place is a time capsule of that period, with brightly coloured posters stuck to the walls. Euston is an excellent example of how the network has adapted over time.

Tim Dunn and Siddy Holloway have a night-time adventure as they go on a late-night exploration of two of London’s least known stations: St Mary’s and the original Aldgate East, they’re only a few hundred metres apart but trains haven’t stopped at either since 1938. There’s nothing on the surface to suggest the stations exist so the only people who know about them are tube maintenance workers. St Mary’s is spooky, with fallen staircases and the intricately designed footbridges hidden high up in the tops of the running tunnel

Tim and Siddy are deep beneath Clapham Common; in fact, they’re so deep, the Northern line is running above their heads. This is Clapham South deep level shelter, an enormous, purpose-built air raid shelter. During the Second World War, as rockets landed on the streets above, thousands of people could sleep down here in more than a mile of tunnels - all built by London Transport in the same way they dug tube tunnels.