Euston station today presents itself as a unified mainline railway terminal with a London Underground station nestled beneath, connecting the two branches of the Northern line and the Victoria line. Historically though this wasn’t the case – the two legs of the Northern line started life at the beginning of the 20th Century as two distinct railways, operated by different private companies, each having their own entrances at surface buildings either side of the old Euston station.

Those private companies were later combined, absorbed into the public London Transport, and in the 1960s the Victoria line came along. This involved extensive rearrangement of the underground space to enable easy cross-platform interchange between the Victoria line and City branch, as well as replacing the old inefficient lifts with escalators. Upstairs Euston terminal itself was completely demolished and rebuilt. All these changes resulted in a section of the original access tunnels between the Northern line branches being made redundant and cut off.

Fast forward to 2016, and the London Transport Museum are organising a series of “Hidden London” tours to visit these abandoned Euston tunnels, and that’s exactly what I got to do yesterday…

The original entrance building to what became the Charing Cross branch of the Northern Line.

This building is threatened with demolition as it sits on the site of the proposed High Speed terminal extension to Euston.

The old ticket hall has been refitted with ventilation equipment for the tunnels below.

Sections of original tilework survive, whitewashed over.

Branded hi-vis mandatory for all visitors.

Connecting tunnels between the the lift landing and platforms. These areas have been repurposed to carry cabling and ventilation equipment.

Our tour guide gives us the background to the tunnel transformation.

Fragments of posters leftover from when passengers last used these areas in 1962 serve as a time capsule.

This passage led to platform level but was plugged when the new accessways were built.

This is the ticket office used to purchase tickets when transferring between City and South London Railway and the Charing Cross, Euston and Hampstead Railway, now both absorbed into the Northern line.

Several of these notices are pasted to the walls, alerting passengers to the imminent closure of these stretches of passage.

This area is also used as storage space for the maintenance staff.

The lift portals which were in service until 1962.

This shaft housed two lifts. Now this serves as an air supply.

This tunnel was installed in the 60s to funnel air to platform level.

The tunnel sits above platforms on both the Victoria and Northern lines. Passengers below would have no idea we could peer down on them.

Spying on travellers on the platforms below.

The tour was very informative, our enthusiastic and engaging guides first giving a background briefing in the old Leslie Green station building before we headed into the main tube station and through a door at the end of one of the Northern line platforms into the abandoned tunnels. There was lots of information given on route and plenty of opportunity for lingering and taking photos. It lasted almost an hour and a half and although not cheap at £35, I came away feeling that it had been worth the price and eager to go on a future Hidden London tour. If you’re a massive transport or infrastructure nerd, it’d be hard to come away disappointed.