The Pneumatic Railway – The Holborn Explosion

Senior Curator Julian looks at tragic events that happened beneath the ground in Holborn.

If you’ve missed my first and second part of The Pneumatic Railway blog, you can click and read about its beginnings and the second experiment with the pneumatic tube system.

Despite the best efforts of the Pneumatic Despatch Company to make the carriage of mail below the streets of London a viable system, the Post Office declined to adopt a transport method that it regarded flawed in many respects. Mail was last carried under air pressure through the company’s tunnels on 31 October 1874.

Front of Wills’ cigarette card number 33 showing the inauguration of the pneumatic tube (2010-0383/33)

On 7 March 1882 the London Gazette carried a notice that the Pneumatic Despatch Company had dissolved but on 6 June 1896, by order of the Court of Chancery, the name of the Pneumatic Despatch Company was restored to the list of Joint Stock Companies.

In 1920 the Holborn Borough Council refused to grant permission for the Post Office to open the streets between Kingsway subway and an existing manhole near the corner of Grays Inn Road in order for them to lay a line of telephone ducts. The council engineer suggested that the old parcels tube be used. An inspection of the tube found that it was still sound but shortly after work had begun the Pneumatic Despatch Company resurfaced, proved their ownership of the tube and demanded some form of recompense.

In 1921 arrangements were made for the Post Office to purchase the whole tube and this was confirmed by the Post Office Tube Acquisition Act 1922. This enabled the tube to be used for the development of the telephone system in London, though obviously a considerable amount of excavation work was still carried out. When purchased, the tube was interrupted in several places throughout its length. Portions had been cut away to make way for subways etc. Some sections had been provided with ventilating shafts but records were scanty. There were at least six shafts within the City limits in 1910, inserted by the City Authorities, of which five remained when the Post Office took control in 1921. These comprised of plain brick shafts, about 24” diameter, fitted with open gratings in the roadways. The Borough of Holborn had also installed six ventilators of similar design in the section of the tube that ran between Grays Inn Road and St Giles Circus. Four of these were still in place when the Post Office took control.

Problems with gas

The installation of ventilating shafts or ducts was an important consideration. During the two years ended 30 September 1904, there had been 21 explosions within the London Metropolitan District as a result of coal gas escaping from subterranean tunnels into electric lights or other road manholes or boxes. These had resulted in eleven people being injured and the death of two horses. The number of explosions each year from escaping gas continued to give cause for concern: 11 in 1925, 10 in 1926, 14 in 1927 and 19 in 1928. In the years following the closure of the tube for postal purposes it had been used for other purposes, without permission and certainly illegally. The Borough of St. Pancras was running electric light and power cables through the section between St Giles Circus and Euston (including Tottenham Court Road and Drummond Street). They had even installed thirteen ventilators, one of which was a ventilated manhole cover, the remaining 2” pipes ran to street refuges, footways or house line. These had been installed to comply with Board of Trade requirements for underground electric lighting mains. They were still in place in 1929 and the Post Office also ran their own cables through this section and through the tube from Euston to Eversholt Street, but ignored the requirement for ventilators.

A disconnected portion of tube was found in the ground opposite 71 High Holborn, this lay roughly parallel with the main tube, about 50 yards (45.7m) long, bricked up at both ends. A ventilation shaft had been installed in this section and remained in position. Elsewhere, some ventilators were removed to prevent debris or water from the street entering the tubes.

The tube running from Denmark Street to Oxford Street corner was used by the Post Office to run cables through, elsewhere it could accommodate up to twenty lead covered cables of the ‘modern type’.

On 25 November 1926 two Post Office employees were working in the length of parcels tube west of West Central District Office (WCDO). Levett (Foreman) and W.G.Fisher (Skilled Workman Class II) were overcome by gas and collapsed within the tube. They were rescued and taken to hospital where they recovered. The cause remained unidentified but coal gas was strongly suspected. Experiments with an electric blower were carried out and these were in use by March 1927, a schedule of blowing foul air from the tubes was introduced at the same time. Once a blower was running, a manhole would be lifted further down the tube to vent any gas.

Tests were carried out in April 1928 and the gas company found small percentages of coal gas at four of the manholes, none was detected at another however the cover situated outside 205 Shaftesbury Avenue revealed 27% coal gas present. This was later traced to a broken 24” (610mm) main which was repaired.

The Holborn explosion

On 20 December 1928 two Post Office employees left WCDO at 07.20 to carry out a scheduled blowing out, or venting, of the parcel tube.  Arriving at the manhole fifteen minutes later W.G. Fisher and A.L. Standley immediately opened the cover to allow any foul air in the immediate vicinity of the shaft to dissipate; the official instruction was to allow twenty minutes for this. This section of tube had been last opened on 3 December. Fisher, the senior man, had worked on this section of the tube off and on for four and a half years. He described the smell that emanated from the exposed tube as a ‘sewer gassy smell’. Thrower arrived, pulling their mobile, electrically powered blower that he had collected from the stores. Fisher warned Thrower that it was ‘a bit gassy’, Thrower replied ‘we have had it worse than this’ before entering the shaft to plug the lead for the blower into the electric point.

The wrecked and exposed Post Office manhole at Holborn. Photographed in the afternoon of December 21, 1928, the day after the explosion underground © BT Archives. POST 33/2829 part 1

The tube at this point carried a number of lead covered Post Office telephone cables carried on bearers 2 ½” x ½” (64mm x 13mm) attached to channel irons bolted to the side of the tube. Also routed through the tunnel were galvanised steel pipes carrying 100 volt electric and power cables. These also provided lighting in the tubes. The electrical socket Thrower was attempting to access received power from WCDO and was placed some four feet east of the inner face of the wall of the manhole chamber. This was on the north side of the tube about three feet above the floor. Fitted with a cover, it was later suggested that this had been the cause of a spark but it was found that Thrower never got as far as removing the cover of the socket when he observed a flame approaching him down the tube. The mixture burned gently at first but gathered violence as Thrower attempted to climb out of the shaft, shouting to his colleagues ‘I am burning’. He was able to get half way out of the tube, with his arms over the top of the hole when the explosion engulfed him, blowing him clear of the wrecked shaft.

The explosion occurred at around 08.00. The ground was shattered, lifted or dropped for a considerable distance in both directions of the tube. The blast travelled beneath the ground, within the tube, between a point near the western end of High Street and the junction of High Holborn and Kingsway. The road was caved in at the corner of Grape Street. Manholes were blown up at Endell Street, 205 Shaftsbury Avenue, Denmark Street, Compton Street and at WCDO. Other than Thrower, eight people were injured and five suffered effects from the gas.

The aftermath of the Holborn Explosion © BT Archives. TCB_417_E05886[1]

The 8″ (203mm) gas main where it junctioned with 4″ (102mm) main at corner of Grape St was fractured. The 24″ (610mm) gas main was cut where it crossed the road outside the Princes Theatre, gas burned outside the theatre up to twenty feet (6.1m) high until late morning. Elsewhere, escaping gas ignited and continued to burn until the afternoon of the following day. Metropolitan Water Board mains suffered over 20 fractures and telephone cables were also cut. Mains and service pipes of the London Hydraulic Power Company were fractured at four points, the most serious being a 6″ (152mm) main. The Film Warehouse, on the corner of Denmark Street and High Street, was set on fire.

Outside the Princes Theatre, Employees of the Gas Company who had been working on the 48” gas main at Shaftesbury Avenue had only recently vacated the site to go for breakfast; this undoubtedly saved them from injury or worse. A taxi cab was overturned and the underground wall of the Holborn Restaurant was blown in by 10” (254mm) by the force of the blast.

The explosion lifted the road for hundreds of metres in both directions © BT Archives. TCB_417_E05881[1]

Thrower’s colleague above ground was Fisher. The gang’s foreman- Levett, reached the scene after the explosion, both of these men were the same two that had been overcome by gas two years previous and were well aware of the dangers. The job of venting the tubes was practically confined to these two men.

Standley had only been employed a few days. Blown off his feet by the blast, he was later found wandering in a dazed state. Thrower’s colleagues had witnessed the flame surround him as he struggled from the manhole:

“he disappeared and I saw no more of him”


41 year old Percy George Thrower was taken to Charing Cross hospital where his charred clothes were cut from him piece by piece, this proved important later when the hospital was asked if a lighter was found on his person. None was found and the cause of ignition never established. Linesman Thrower had worked for the Post Office for seventeen years and had been married for fourteen years and had two children; one aged eighteen months the other fourteen years.  He died at 18.20 on 26 December 1928; the official cause of death was recorded as Toxaemia following burns.

Next week, in my fourth and final part of The Pneumatic Railway blog, I will explore the aftermath of the explosion and remaining survivors of the pioneering railway.

– Julian Stray, Senior Curator

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