By Philip Eden
It was among the 20th century's worst sporting disasters. The Derby Day storm of May 31, 1911 - a century ago - was one of the fiercest thunderstorms ever to hit London and its suburbs, and in the metropolitan area 17 people lost their lives.
There were actually several distinct storms that afternoon, but the worst of them broke over Epsom Downs towards the end of the day's racing, and at nearby Banstead two separate rain gauges measured respectively 91mm and 89mm. A little further away, Chipstead reported 76mm and Bletchingley 75mm. Meanwhile, in the town centre of Epsom, according to the official observer, a total of 72mm was collected, most of which fell in just 50 minutes.
The degree of electrical activity was stupendous. The amateur meteorologist, Spencer Russell, who lived in Epsom, wrote:
"Forked lightning was first seem at 5pm, and from then until 7pm lightning and thunder were practically continuous. Rolling thunder was entirely absent, the peals coming in sharp decisive cracks, resembling cannonading, whilst the lightning flashes were of dazzling intensity. Between 5.30 and 5.45 pm a count of flash frequency yielded 159."
Russell also determined that, within a three mile radius of Epsom, three people were killed instantly, 14 more were injured, one of whom died later, and four work horses were also struck and killed. Of the three who died, two youths who had been sheltering against a reservoir wall were struck by lightning, while the other was a man driving a horse and trap across Epsom Downs.
A more recent local meteorologist, John Bird, gleaned the following editorial from a contemporary newspaper:
"It would have taxed the skill of the finest word painter to describe the scene at the height of the storm. It was an inferno of water, mud, thunder, lightning and hail. Innumerable cars hors de combat, horses plunging with fright, a confusing heap of figures inextricably jumbled together in narrow roadways, half-drowned pedestrians, drenched cyclists, terrified women and children, and battalions of men helpless against the mighty powers of nature in one of here savage moods."
The railways in the district were also in serious trouble, with landslips in cuttings at Merstham and Coulsdon, and flooding to the height of the train footguards at Epsom station.
© Philip Eden