Did you know that the world's worst roller coaster accident happened right here in London? Five children were killed and 13 injured at Battersea Park Fun Fair, when a malfunction caused their big dipper train to hurtle backwards.
You'd think such a tragedy would be well known, especially as it occurred as recently as the 1970s. Yet it seems the event has largely slipped from public consciousness, and not just among those too young to remember the fair*.
Battersea Park Fun Fair — established during the Festival of Britain in 1951 — was a hugely popular destination for family thrills. Its most famous ride was the Big Dipper, a notable presence on the park's skyline that attracted long queues. It was the London Eye of its day. The Duchess of Kent and her children took a ride in its opening year, while the Bolshoi Ballet climbed aboard in 1965.
Late in the afternoon of 30 May 1972, tragedy struck. 31 people had boarded a three-car wooden train. As it reached the top of the first incline, some 15 metres above the park, it was prematurely detached from the drive chain. Despite the best efforts of the brake man, the train slipped backwards under its own momentum on a 1 in 3 gradient. At the bottom, it hit a tight turn and derailed. The lower carriage was crumpled by those behind. Two teenage boys and an eight-year-old girl died at the scene, and two other children died later . One of the survivors recounts her experience here.
The disaster led to a review of fairground safety, and several charges of manslaughter. Prosecutors described the ride as a 'death trap', citing dozens of flaws and safety concerns. Despite the accusations, the park's general manager and the ride's engineer were both cleared of the charges in November 1973 .
It wasn't the first mishap on the ride. In May 1951 an empty car derailed, knocking over a parapet. Nobody was hurt on that occasion, although several passengers were marooned for 20 minutes. A similar incident to the fatal crash seems to have occurred in 1968, when a woman broke her arm. In May 1970, £400,000 worth of damage was inflicted on the ride following a suspected arson attack. It was closed for two months.
The Big Dipper was permanently closed and dismantled soon after the accident. It was replaced by a more modern steel roller coaster known as The Cyclone. But the iconic dipper's retirement led to a swift decline. Coupled with development wrangles, the fair's fortunes dwindled until it finally closed in 1974. Temporary fairgrounds would occasionally set up in the park throughout the 1970s, but a permanent attraction like that established in 1951 would never again take root.
Note: we appreciate that for the families of those involved this is certainly not a 'forgotten tragedy'. We include it in this series, however, as we feel it deserves to be more widely remembered.
 Court report from The Times, 27 Feb 1973
 The Times, 20 Nov 1973
*We base this assertion on a show-of-hands at three recent talks, including to a group of London historians. In each case, only one or two people in the audience had heard of the disaster.
Several other sources were used. Please contact the author for more information.