Who is responsible for changing the time on Big Ben?
There is a dedicated team of five people who look after the 154-year-old timepiece, headed up by Steve Jaggs who is Britain’s official ‘Keeper of the Great Clock’.
Those in the team include Ian Westworth, lead engineer Mike McCann, Paul Robertson and Huw Smith.
All the 2,000 clocks inside the Houses of Parliament will be turned back at the same time (well just afterwards), working throughout the night to ensure they all show the correct time.
How long does it take?
The mission to turn back the giant hands on Big Ben’s four clock faces takes an incredible FIVE hours in total.
The team will begin at 9pm on Saturday 28 October and finish at around 2am. At 2am the clocks must ring out to announce British Summer Time too, a deadline that has never been missed – so the pressure is on.
How do they change the time on Big Ben?
The Big Ben team must first climb the 334 steps inside the Elizabeth Tower. They already do this three times a week – with some of the team having done this for more than a decade now.
Once at the top they move into the belfry where the sound of ticking is meant to be particularly striking.
‘The beauty of the mechanics is what intrigues all of us. It runs on remarkable precision and the fact it is more than 150 years old is extraordinary,’ Ian Westworth once explained.
Inside the belfry the clock is inspected with the clock’s chimes turned off. The lights on the dials are then switched off so the clock hands can be moved without confusing people.
Ian Westworth said: ‘After the job is done you realise just how privileged you are. When I walk over Westminster Bridge and see the thousands of people taking pictures and waiting for the hour strike it is charming to know I am part of that.
‘You forget the eyes of London are on you until you’re back down on the ground – and you have kept the country running on time.’
Here’s the breakdown:
21.05 (BST): The hour strike is locked off Big Ben, the Great Bell. It is re-set for the strike at 02.00 (GMT). The hour bell is silent until then.
21.46 (BST): The quarter chimes are also locked off. This stops them chiming while the clock is being inspected.
21.48 (BST): The dial lights are switched off. This allows the clock hands to be advanced without drawing too much attention or causing public concern.
21.50 (BST): The clock hands are advanced to 12 midnight by releasing the double three-legged gravity escapement. The escapement regulates the clock’s accuracy.
Releasing the escapement allows the weight which drives the clock mechanism via the going train to rotate freely. This advances the hands forwards. The process takes two minutes.
At this stage, great care must be taken to make sure the clock hands do not overrun past 12. If this happens the hands would have to be advanced right around until they reached 12 again.
21.52-23.00 (BST): The going train is stopped. This time frame is used to carry out inspections as part of a rolling maintenance programme.
00.00 GMT (01.00 BST): At the new midnight, the going train is started. The clock then runs for the next two hours – without the hour strike or quarter chimes. This period allows the clockmakers to monitor the clock’s accuracy and make any adjustments to get it within one second of the new time.
01.46 (GMT): The hour strike and the quarter chimes are unlocked. This allows the hammers of the hour bell and quarter bells to operate at the next strike.
01.58 (GMT): The dial lights are switched back on in the following sequence: West, South, East, North.
02.00 (GMT): The quarter bells sound the Westminster Chimes, the Great Bell strikes the hour and the time change weekend procedure is complete.
Will the public be able to see the hands spinning round from outside?
Steve Jaggs said there should be enough ambient light for members of the public to see the clock hands spinning around the clock faces. People do turn up to watch and this year there will be night tube so it will be easy enough to get home afterwards too.
Things you might not have known about Big Ben
1) The nickname ‘Big Ben’ actually refers to the bell rather than the clock tower. The bell is believed to have been named ‘Big Ben’ after Benjamin Hall who was the First Commissioner of Works when the tower was constructed between 1825 and 1859.
2) The tower was renamed ‘The Elizabeth Tower’ in 2012 for the Queen’s Diamond Jubilee, it was previously called ‘the Clock Tower’.
3) The 13.5 tonne clock has a light at the top of the tower, which is believed to have been installed so Queen Victoria would know when Parliament was sitting. The light is turned off afterwards, which in a pre-telephone era, would prompt the Queen to expect a visit from her ministers. Nowadays it is lit at night so the public know when they are in session.
4) Pennies are used to keep Big Ben running on time. Steve Jaggs recently told Westjet Magazine: ‘The pendulum swings back and forth at two-second intervals. Depending on the time of year, the air can become thick, so the pendulum takes longer to swing. One old penny placed on top of the pendulum speeds up the clock by two fifths of a second over a 24-hour period. We like to keep the clock within two seconds of accuracy. At the moment, we’ve probably got about 30 pennies on there.’
What is next for Big Ben?
In January there is going to be a major restoration project that will take three years to complete. This means scaffolding will go up and the team will check the condition of the roof of the Elizabeth Tower.
The clock itself will also be taken apart so it can be refurbished. The bell itself will be dyed and x-rayed for fractures plus the pendulum, located in the weight shaft, will be inspected for the first time since the tower was constructed.