Something to look out for — as people will be abseiling down Big Ben’s clock face next week*.
Abseiling technicians will clean each of the four dials of the clock and inspect for damage, working at a height of around 60 metres.
One week has been set aside for the cleaning to take place, allowing one day for each clock face and contingency in case of poor weather conditions. Last cleaned in August 2010, the Great Clock has four dials, each made up of 312 pieces of pot opal glass, held together by a cast iron framework. The clock hands are made of hollow copper sheet, which replaced the original cast iron hands when they proved too heavy.
As well as removing the dirt which has built up over the last 4 years, the technicians will carry out a photographic survey to check the clock dials for damage.
The Great Clock will continue to measure time throughout the cleaning process, but the hands of the clock will be temporarily paused as each side is washed. Clock mechanics will take this opportunity to carry out essential maintenance to the mechanism that moves the clock hands.
Additionally, workers will wear ear defenders to protect their hearing from Big Ben’s trademark chimes.
*Ben Ben, the colloquial shorthand for the tall tower, the clock, the prison cell and everything associated with a bloody big bell and a clock in a tower next to Parliament.