Buñol celebrates the Tomatina: 145 tonnes of tomatoes thrown by 22,000 participants

Buñol – about 20 kilometres west of Valencia off the A-3 Valencia-Madrid motorway – is normally a sleepy market town of 10,000 inhabitants with a moderate British expat community settled there and in neighbouring towns.

Except on the last Wednesday of August every year, that is.

This, known as La Tomatina, is the date when lorry-loads of ripe tomatoes are poured into the main square at 11.00 on the dot, and participants – many of whom have travelled from as far away as Japan or Australia – get exactly an hour to hurl them at everyone else.

Nobody is allowed to start before the horn blows, and when it sounds again at noon, they have to stop right there.

Chucking tomatoes at faces or heads, or pulling at people's clothing, is not allowed, but the impact of 145 tonnes of salad fruit means whatever participants are wearing at the time will no longer be worn again, or even suitable for cleaning the car with.

Showers on site permit them to rinse off the worst of the pulp from their hair and skin – meanwhile, the 'red current' flowing through the central Plaza and neighbouring streets continues to be about a foot deep.

Somehow, by the next day, all traces of the world's biggest open-air bowl of tomato soup will have disappeared by the last Thursday in August, if not earlier – by which time, millions of social media users will be viewing the photo and video footage of the morning's food fight with feelings ranging from disgust to hilarity and horror to excitement; in any case, the festival's antics never leave anyone indifferent.

This morning saw 22,000 tomato-throwers gather in Buñol on what was the 73^rd edition of the annual Tomatina festival, the origins of which are, unlike most Spanish fiestas, neither religious nor complex nor rooted in legend, magic or tradition.

The Tomatina basically started in the 1940s when a group of lads at the weekly fruit and veg market became bored and started throwing the contents of the stall around.

They were arrested, but to show how little they cared, they returned on the same weekly market date the following year and repeated the performance.

It caught on quickly and became an official annual festival which has since been replicated elsewhere in the world, particularly in South Korea after tourism bosses visited the Valencia province to find out more about it.