As you step through the familiar terracotta frontage of an old tube station it’s difficult to believe you’re two floors above ground, and not deep under it. Yet that’s what’s been achieved inside the London Transport Museum, where they have turned a normally austere white exhibition space for artworks into the dark grimy underbelly of London.

It’s an exhibition about Hidden London, the unseen spaces that were once thronging with passengers but were slowly sealed off as stations were rebuilt. A number of them are now open for heritage tours, and the museum expects around 20,000 people to go on a Hidden London tour this year. But here in their museum, they’ve also created what could be described as a trailer for the tours.

The exhibition though goes into more detail than can often be included in the tours, which of necessity cannot carry a lot with them. There’s a lot on display, from old maps to film posters and lots of photos of what the tunnels used to look like. Loads of old maps and diagrams show off the size of the hidden spaces, and plenty of old signs warning of stations being closed, or WW2 shelters being used.

If that was all, it would be informative and interesting. But that’s not all. What makes the exhibition more than just a collection of objects is how they’ve decorated the space — replicating the effect of being deep underground in disused tunnels.

Dark dimly lit spaces fill the rooms. The spiral staircase normally all shiny steel and glass is now a dirty escape staircase lined with old iron rings and warning signs. A space to peer down through a gap and watch a tube train arrive in the platform beneath your feet, and yes, there is a blast of air as the train arrives.

One of the scary thrills of being in some of the tunnels is being a grill away from trains rushing past old doors — and in here, there is an all too realistic replica. It may be just a video screen, but the floor shaking and load roar is almost scary to stand next to. In an exciting sort of way.

All around, clutter from the underground gives a very real sense of being in a working space, old posters line the walls, cables and dirt fill the gaps, and workman’s lamps swing in the hot breeze.

Elsewhere, they’ve recreated the Clapham South shelters as they were during, and also after the war when they were used as temporary hotels for the Windrush generation. You come out blinking from the underground tunnels into the 1st floor landing, which is delightfully disorienting.

One of the other aims of the exhibition is also to show off the deep underground spaces to people who would not normally be able to use the many stairs to get down to them — as the exhibition has a lift, and for people who sometimes struggle with confined spaces, the exit is just around the corner not a long climb up a staircase.

The Hidden London exhibition opens on Friday and is included in the entry price for the museum, which also gets you repeat visits for a year.