But instead of flying forward at great speed, after a perspex domed roof is closed over my head, we gently trundle along a narrow-gauge track into the tunnel, meandering through an underground network until we reach an eerily quiet, abandoned platform.
Only a dartboard on a wall remains from when dozens of workers toiled around the clock, loading bags of letters and parcels from the Royal Mail sorting office 70ft above at Mount Pleasant in Clerkenwell on to mail cars to distribute across London via a network of secret underground tunnels.
I was one of the first people lucky enough to take a 15-minute ride around a loop running two-thirds of a mile from a maintenance depot to the east and west platforms at Mount Pleasant, passing a “train graveyard” where a line of red liveried mail carts were left when the service closed in 2003.
Two brand new miniature trains which can each carry 32 passengers will transport visitors on the Mail Rail line from September 4 as part of a new visitor attraction to preserve the heritage of the underground mail delivery network.
When it was launched in 1927 the service ran on one of the first electric-powered rail lines in the world, with horses and carts still plying among the motors on the congested roads of the capital above.
The 220 staff working on the 6.5-mile route from Whitechapel in the east of the city to Paddington in the west helped cut the journey time for mail carts from two to three hours, to just 30 minutes.
Its launch had been delayed by the First World War, when the narrow tunnels were used to hide the Rosetta Stone and other treasures from the British Museum and National Gallery, in case of invasion.
After opening it ran around the clock for 76 years, linking six sorting offices, with mainline stations Liverpool Street and Paddington, delivering up to four million letters a day at its peak.
When it was struck by a bomb during the Second World War it only closed for a day, yet the soaring cost of keeping it running compared to deliveries by road finally sounded its death knell.
Despite its tunnels being smaller than those on the Tube network, the scale of the subterranean network is startling and when you visit it’s easy to imagine Royal Mail liveried carts trundling along the tracks, stopping at platforms along the route every seven minutes for a bustle of activity while being loaded and unloaded.
In between deliveries the men would have a cup of tea and a chat or throw a few arrows at a dart board before jumping into action when the next one arrived.
Interactive displays in the maintenance depot, where carpenters, electricians and engineers repaired the mail carts, show how a pneumatic tube just a few feet underground was used for the first mail delivery system along a short route from 1863 to 1874.
This was replaced by a fleet of 90 fourwheel railcars on the electric tracks 50 years later.
The nearby Postal Museum, which has already opened, has an exhibition showing how the Royal Mail developed from transporting letters ordering troop movements by horse for Henry VIII in the 16th century to the present day.
On display are Royal Mail coaches used with horses in 1800, the first green pillar boxes installed in the Channel Islands in 1852 which were seen as dreary and replaced with red ones and a Morris Minor van from 1935 which replaced horse and cart deliveries.
The Postal Museum and Mail Rail is a fitting tribute to British ingenuity and well worth a visit.
GETTING THERE
The Postal Museum (0300 0300 700/ postalmuseum.org) offers tickets from £16 per adult, £8 per child.
London tourism: visitlondon.com
