On 19 January 1917, in the darkest days of the Great War, a massive explosion rocked London's East End. Shockwaves could be felt in Essex, while the blast itself was heard as far away as Southampton and Norwich. But the firestorm wasn't caused by the sinister German Zeppelins that were making increasingly frequent appearances on London's skyline. In fact, the roots of capital's biggest ever explosion were much closer to home: a TNT factory in Silvertown.
From the outset, the management of the former Brunner, Mond and Co. chemical works expressed their concern about government plans to turn their plant over from the production of caustic soda to TNT for munitions. TNT is a highly unstable substance and the factory was in a crowded urban area. The Metropolitan Building Act of 1844 made it illegal to carry out 'harmful trades' inside the boundaries of London. But Silvertown was just outside this boundary, and its plentiful supply of labour and easy access to ports made it too good a location to overlook. In September 1915, the management caved to government pressure and the plant was soon making nine tons of TNT a day.
Sadly, the management's concerns were founded. The explosion that ripped through the factory on that fateful Friday evening instantly destroyed part of the factory and several nearby streets. It showered molten metal across several miles, starting wild fires that could be seen as far away as Kent and Surrey.
More than 900 homes near the plant were destroyed or badly damaged in the disaster, leaving thousands of people homeless. Between 60,000 and 70,000 buildings were damaged to some extent, including a gasometer over the river in Greenwich which blew up, spewing 200,000 cubic metres of gas into the air in a massive fireball. Factories, docks and warehouses were also decimated. The eventual repair bill was around £250,000 – a staggering amount of money at the time.
Even more serious was the human cost. Seventy three people died that day. More than 400 were injured, 94 of them seriously. One man lost his wife and four children, aged between 10 and 13. The dead also included many firemen from the local station, along with dock and factory workers and children, asleep in their beds. But the death toll could have been much worse: by a stroke of luck, the explosion happened at just before 7pm, after most people had left the factory for the day and before they had gone to bed (most of the damage to homes was to the upper floors).
The precise cause of the explosion has never been found and rumours abounded of sabotage by a German spy or that the factory had been hit by a German bombing raid. The most likely explanation is much more mundane – that fire broke out in a melt-pot room and quickly spread to railway wagons where 50 tons of TNT was waiting to be moved. The inquiry found that the site was totally unsuitable and that Brunner Mond had failed to look after the welfare of its staff. The government chose not to publish the findings until the 1950s.