During the week of 18 August Parliament’s Great Clock, also known as Big Ben, will undergo essential maintenance. 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.