London Pneumatic Despatch Company

In 1859 Thomas Webster Rammell and Josiah Latimer Clark proposed an underground tube network in central London "for the more speedy and convenient circulation of despatches and parcels".

With initial funding of £25,000 (£3,163,086 in 2023),[4] the company tested the technology and constructed a pilot route at the Soho Foundry of Boulton and Watt in Birmingham.

A permanent line of 2 ft (610 mm) narrow gauge was constructed between Euston railway station and the North West District Post Office in Eversholt Street, a distance of approximately a third of a mile.

[7] A journalist made a report on the first scheme at Euston: Near the bottom of Euston Square, there is the mouth of the tube, and there are the travelling trucks, ready to be thrust into it; and as we look, a bell rings at some distance up the rail – this is a signal that a mail-train has arrived... At this signal we hear a shovel of coke thrown into a furnace, a small steam-engine begins to beat swiftly... the pneumatic wheel ... is twenty-one feet in diameter, and is composed of two discs of iron...

Here, then, we have the means of pulling or pushing the travelling carriages along their subterranean road, and as we speak we see it in operation: for a mail-guard opens a door, throws in two or three mail-bags just snatched out of the guard's van as it rolls into the [mainline] station, the iron carriages are shoved into the tube, the air-tight door at its mouth is closed... and we hear them rumbling off on their subterranean journey at a rate, we are informed, of twenty miles an hour... a bell connected with an electric telegraph warns him that the attendant at the other end of the tube is about to thrust the carriage into the tube on its return journey.

It has been pushed along... by the pressure of air thrown out by the wheel, but it has to be pulled back by suction; the valve of the suction-pipe, in the connection with the centre of the disc, is accordingly opened, and speedily we hear a hollow rumbling, and out shoots the carriage, ready once more for fresh bags.The company sought to develop further lines within London, and attempted to raise an additional £125,000 (£15,107,276 in 2023),[4] of capital.

[9] The first 'trains' ran on 10 October 1865 after a demonstration in which the chairman, Richard Temple-Grenville, 3rd Duke of Buckingham and Chandos, travelled from Holborn to Euston in one of the capsules.

By the time of the 1866 financial crisis caused by the Overend, Gurney and Company collapse, a 3⁄8-mile (0.60 km) tube from Holborn to Hatton Garden had been constructed.