Large coke in Piccadilly

Coca-Cola unveiled one of the world's biggest and most sophisticated billboards today in the heart of the West End.

The 30-metre-wide neon colossus can respond to the weather and interact with people looking at it from the ground.

The billboard was switched on in Piccadilly Circus at dawn, lighting up with the message "Hello London" in the drinks giant's trademark red and white.

It's the biggest billboard in Britain and the widest in the world, beating even the monster Coca-Cola sign which reigns over Tokyo's Ginza shopping district.

The billboard is three times bigger than the previous Coke sign on the same site.

Coca-Cola has described the billboard as "an intelligent sign, with state-of-the-art computer technology, built-in cameras and an on-board heat sensitive weather station."

The sign can respond to weather and movement.

"When it's raining, big drops will appear on the screen and when it's breezy, the Coke sign can ripple as if it's being blown by the wind," a spokeswoman for the company said.

It will also be able to recognise if people are waving at it from the ground below and, eventually, will be able to respond to text messages from mobile phones.

Coca-Cola has had a billboard at Piccadilly Circus, the advertising heart of London, since 1954.

The lights in the circus have been switched off only five times since then, including in 1974 when a miners' strike triggered electricity shortages and in 1997 for the funeral of Princess Diana.