On this day 50 years ago the largest and heaviest hailstone officially recorded in the UK fell at Horsham, Sussex. On a hot and humid day around 6pm the sky turned ink-black. “The storm struck like a bomb . . . within a few minutes the air seemed to become a solid mass of rain, hailstones and crushing wind,” reported the West Sussex County Times. Residents likened it to an air raid, and one woman described being struck on the head. “At first I thought I had been struck by lightning. I was almost knocked out”, while another witness said: “It sounded like a lot of machine gunning, the noise of cracking glass was terrible.”

Hundreds of roofs were smashed, windows shattered and apple trees stripped bare. The record-breaking hailstone weighed 190g (6.7oz) and measured 6.35cm (2.5in) in diameter, heavier and larger than a cricket ball. It was astonishing that only three people were injured and none was seriously hurt.

A tornado also tore through the outskirts of the town, sending chimneys crashing through roofs and uprooting trees. A petrol station was blown apart, with little more than its walls standing, a petrol pump thrown into the middle of the road, and the corrugated roof flung a quarter of a mile away.

The hailstorm cut a swath through Sussex, forcing an aircraft to make an emergency landing at Gatwick after being badly damaged by giant hailstones. Thunderstorms swept the whole of southeast England and brought chaos with widespread flooding that cut road and rail links, while lightning set fire to two fuel storage tanks at an oil refinery in Kent.