But killer treacle? It could only happen in America - Boston, Massachusetts, to be precise. And the deadly substance in question was molasses, the brown sticky by-product of sugar refining that is used by the baking and distilling industries.

In the early years of the 20th century, Boston was the distilling capital of the US, and its shore was lined with storage tanks containing millions of gallons of molasses. One tank in particular was more than 50ft (15 metres) tall and held about 2,320,000 gallons (10.5 million litres). It belonged to a company called US Industrial Alcohol and, by 1919, it was causing concern. The giant cylinder had taken to leaking, either because of structural weaknesses, over-filling or both. The company was warned about this and responded by painting it brown to make the leaks less noticeable.

Tragically, no amount of painting could hide the reality of what was about to happen.

January 14 began icy cold. But, by the next day, temperatures suddenly soared to unseasonable levels, causing rapid expansion and possibly some fermentation inside the tank. It was more than the structure could bear. At 12.40pm there was a sound like a crack of thunder as the steel plates tore apart, releasing a wave of hot molasses into the surrounding streets.

Buildings collapsed or were blasted from their foundations, and a fire station was knocked over. Flying steel plates severed the girders of an elevated railway, and a train was lifted bodily into the air. Eyewitnesses reported a wall of treacle up to nine metres high moving at around 30mph (48kmh) in the area surrounding the tank. The sticky flood was impossible to outrun and horses, trapped like flies on flypaper, had to be shot where they stood. Twenty-one people died that day and a further 150 were injured.

The clean-up operation took six months, during which time the harbour remained a stinking, filthy brown.

Thirty years later, Bostonians were still reporting that, on hot days, molasses could be seen oozing from cracks in the pavement.