Mail Rail: The Railway Beneath London's Streets

Original non-fiction text written for Revision Library.

For most of the twentieth century, hidden more than twenty metres below the busy streets of central London, a secret railway carried millions of letters and parcels every single day. There were no passengers, no windows, and no daylight: only small, driverless electric trains rattling through narrow tunnels in the dark.

The Post Office Railway, later nicknamed Mail Rail, opened in 1927 after almost twenty years of planning and construction. Engineers had grown frustrated watching horse-drawn carts and delivery vans crawl through London's ever-worsening traffic, so they proposed something radical: a miniature underground railway built purely to move post, running six and a half miles between Paddington in the west and Whitechapel in the east.

The trains themselves were barely large enough for a person to sit inside comfortably, which was exactly the point; they were never designed to carry passengers, only mailbags. At its busiest, Mail Rail moved around four million letters a day, gliding silently beneath some of London's most famous streets while the traffic above crawled along, entirely unaware of what lay beneath.

"People are always astonished to learn how long it operated," explains Dr Isla Ferguson, a transport historian who has studied the railway for over a decade. "For seventy-six years, Mail Rail quietly kept the city's post moving, through the Second World War, through strikes, through decades of change on the streets above. Almost nobody who used the postal service ever gave it a single thought."

Despite its long service, Mail Rail was finally closed in 2003. Royal Mail decided that transporting post by road had become considerably cheaper than maintaining a private underground railway, its stations, and its ageing fleet of trains. For over a decade afterwards, the tunnels sat silent and unused, visited only occasionally by engineers checking that the structure remained safe.

In 2017, however, a short section of Mail Rail reopened to the public for the first time in its history, as part of a new postal museum built above one of its old depots. Visitors can now ride a small train through part of the original tunnel network, experiencing, in miniature, the same dark, narrow passageway that once carried the nation's letters. Some historians argue that the railway should never have closed at all, pointing out that London's road traffic has only grown worse since 2003; others maintain that reopening even a short stretch as a visitor attraction was a fitting way to preserve a genuinely remarkable piece of engineering history.