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In 1927, Britain’s Royal Mail was thriving. The vital artery of British society was delivering four million letters a day and to keep on top of the continuous flow, a railway was built under the streets of London: Mail Rail.

Formally known as the Post Office Railway – but fondly referred to as Mail Rail following a 60th anniversary rebranding – the railway’s electric trains navigated a 6.5-mile network of narrow tunnels, which stretched from Whitechapel in east London to Paddington in the west, linking six Post Office sorting offices with Liverpool Street and Paddington stations.

Located 70ft below ground level, up to 220 engineers, cleaners and workers lugged bags of parcels back and forth from wagons to station platforms and kept the system running 22 hours a day, only leaving two for maintenance.

Post Office underground railwayman operating a shunting vehicle in 1935. Credit: Royal Mail Group.


The idea of the underground line was first mooted in 1855 and with mail travelling as slow as 7mph in the capital’s congested streets, by the 20th century an alternative method was required.

Work began in 1914. The tunnels were dug by hand using the greathead shield method, where workers dug away in a huge drum-like shield, a technique that was used in the construction of many of the underground lines. Cast iron segments were then bolted together to form the tunnel lining.

Tunnelling was complete in 1917 but the onset of World War One saw the project paused as resources were reprioritised. Not that the incomplete system didn’t play its part. Safe and underground, the tunnels were used to store art belonging to the National Portrait Gallery and the Tate Gallery and even the Rosetta Stone was housed in its walls during the war.

Finally, on December 5, 1927, the 2ft gauge railway line opened. In total, three types of rolling stock ran on Mail Rail. The original fleet of 90 trains had to be replaced within three years because of excessive wear being caused to the track. New rolling stock was introduced in 1930, with each 27ft car able to carry four mail bag containers, which held an average of 15 bags of letters or six bags of parcels. Replacement trains were trialled in the 1960s and a new fleet introduced in 1980.

Through declining use and closure of the above-ground offices, the system became uneconomical to operate and in 2003 it was closed for good.

Over time, as the activities of smaller sorting offices were absorbed by larger centres, the amount of mail being moved between offices fell. For example, the Mount Pleasant Mail Centre in Islington is now one of the largest sorting offices in the world and does the work of what four sorting offices would have previously completed.

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The Mail Rail Car Depot. Credit: Miles Willis.
The Mail Rail Car Depot. Credit: Miles Willis.


For years since, Mail Rail has remained abandoned, until now. Despite being built for mail rather than man, the 90-year-old railway will be open for the public to ride in September, following the launch of the £26 million Postal Museum.

London’s latest tourist attraction will guide visitors through five centuries of Britain’s postal heritage with the little-known underground line promising to be the star attraction.

Stepping across the road from the museum and into the former engineering depot, tourists will be met with interactive displays, reading material and the main attraction: a ride on Mail Rail. Once onboard, visitors are taken on a 20-minute audio-visual tour as one of two miniature trains – one in the original Post Office Railway green and the other in the Mail Rail red – crawls through the tunnel’s passages, which are as narrow as 7ft.

In its heyday, Mail Rail trains travelled at speeds of up to 35mph but visitors will be treated to a leisurely pace of 4mph.

Also, unlike the originals, these trains are driver operated and built by Severn Lamb, which won a tender for two purpose-built, battery-powered trains in 2015.

A new Mail Rail passenger train. Credit: Miles Willis.
A new Mail Rail passenger train. Credit: Miles Willis.


But Mail Rail might not have been restored had alternative plans been brought to life. Drumming up ideas for how the deserted underground system – which starred in the 1991 Bruce Willis film Hudson Hawk – could be used, one suggestion was to turn the network into a mushroom farm and another to transform it into a cycle highway. For a number of reasons – the tunnel’s practical constraints for a start – neither idea got o the ground.

‘There’s always an interest that builds around something that’s hidden, the idea that it’s something underground and abandoned, the intrigue of it,’ says
the museum’s curator Chris Taft, the go-to expert on all things Mail Rail. ‘And also Mail Rail was never designed for the public to see as such. It was never secret but it wasn’t there for the public to come and look at. So many people have never seen it.’

Postal Museum director Adrian Steel adds, ‘We’re anticipating a very busy first month, with lots of fun activities planned for families. Then, on Monday September 4, Mail Rail trains depart for the first time – a truly historic moment for London.

‘The museum itself opens up the chance for people to gain an insight into some of the quirky social history behind an incredible British invention – the post, whilst Mail Rail affords people a once-in-a-lifetime opportunity to explore a slice of subterranean London previously hidden from the public view.’

Royal Mail is a different animal now to what it was in the early 20th century but its legacy as the ‘first social network’ will live on thanks to Mail Rail and the Postal Museum.

The Postal Museum opened to the public on July 28 in Phoenix Place, London. Mail Rail is scheduled to open on September 4. General admission to the Postal Museum and Mail Rail (including a voluntary donation) costs £16 for an adult and £8 for a child.

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