ECJ EUROPEAN Cleaning Journal

One of the world's most famous landmarks - Big Ben in London - is having a makeover this week as four window cleaners have been working hard buffing and shining the 312 pieces of glass that make up the iconic clock face.

This is no ordinary cleaning job for the four men, who have been dangling 60 metres above the ground and wearing helmets and climbing gear to carry out this delicate operation. The Great Clock was last cleaned in 2010.

Paul Robeson, chairman of the British Watch and Clock Makers' Guild, told the BBC's Today programme the cleaners were "very brave or mad, one or the other".

He said: "The glass panels over the clock face are terribly thin and fragile, because originally the dials were lit by gas, which is very dim. Birds can fly into them and break them. This is why our window cleaners have to be extremely careful.

"It's no longer the biggest clock, it's no longer the biggest bell, it's no longer the tallest clock, or any of those things. But it is the most famous the world over."

The stopping of each side's clock for cleaning has also given technicians a chance to carry out essential maintenance on the 155-year-old mechanism.

Both hands were designed to be made of cast iron, but that proved too heavy, so gunmetal was used instead.

But the minute hand was still too weighty and would struggle up to the point of midnight before dropping down four minutes in one go, so had to be replaced with a hollow copper equivalent.