As the clocks go forward, meet the man in charge of the world’s most famous timepiece

Should you happen to be standing near the Houses of Parliament this Saturday evening, you’ll notice two things: first, at 8.30pm, all four faces of Big Ben will go dark. Second, at around 10pm (if you have keen eyes), you’ll spot its gigantic hands starting to race round.
 
This is the night that the clocks spring forward an hour. For the rest of us, it heralds the start of British Summer Time and an extra evening hour of sunlight, but for the people who have to change Big Ben it means a hard slog until 2am.

The Palace of Westminster has three full-time clockmakers who look after its 2,000 clocks, of which the most famous is the one we all call Big Ben (though, in fact, that’s the name of the bell inside the Elizabeth Tower).
 
One of the clockmakers, Paul Roberson, who is also the chair of the British Watch and Clockmakers’ Guild, still can’t believe his luck at having this job — even though it means getting in at 7am, being on call all hours, and climbing 334 stairs up to the top of Big Ben three times a week to wind the clock, because there’s no lift.
 
What if you leave a spanner at the bottom? “What do you think?” he asks. Once he had to go up and down 10 times in a single day, doing repairs. “But the worst thing,” he laughs, “is leaving your pass at the top when you’re heading home.”

Roberson trained as a watch and clockmaker in Hackney. “I’ve always been mechanically minded, but this is more fun than rolling around under a car, he says.
 
TIME TO TEST

The clock mechanism itself was designed by an eccentric barrister-turned-horologist called Edmund Beckett Denison, and made by Dent of Pall Mall, in London. It was finished in 1854 but, Roberson explains, the Houses of Parliament were way behind schedule, so there was time to thoroughly test the mechanism.
 
“Then it was one of the wonders of the world,” he says, admiringly. No one believed such a huge clock could be accurate to the second, but it was and, according to Roberson, “I see no reason for it not to go on working for ever.
 
“When I first heard Big Ben, I expected the noise would blow my brains out but, in fact, because of the way sound carries, it almost seems louder outside. And it keeps humming afterwards. The sound of its chimes, which we call the Westminster chimes, are in our blood, but they are copied from the Cambridge chimes.”

Big Ben is called a three-train clock because it has three sets of weight-driven gears, or “trains”. One runs the quarter chimes, one runs the strike, and one, the “going train”, runs the four sets of hands. This train is still manually wound three days a week using a crank handle, winding its weight right back up to the top of the tower.

WOUND UP
It’s hard work and the men take turns, at about 30 turns each. It takes an hour to wind. The other trains have been wound by motor since 1912. Because Big Ben has to be accurate, the clockmakers have a tried and tested system that is reassuringly low-tech.

To check that Big Ben’s chime is spot on, they phone up the speaking clock just before the hour, then belt up to the belfry with a stop-watch to check the accuracy of the strike. If it is a tiny bit out, they place pre-decimal pennies on the pendulum to make adjustments. Adding one penny speeds the clock up by two-fifths of a second over 24 hours; taking one off does the reverse.

Just twice a year, when the clocks change, the clockmakers are allowed to stop the clock (that’s when the clock faces go dark). This gives them precious time to do any necessary maintenance.

So on Saturday, at precisely 9.05pm, the strike will be “locked off”; then, at 9.46pm, the quarter chimes as well. Just before 10pm the hands will whizz round to move the time forwards, to midnight — making sure they don’t overrun, or they would have to go all the way round again. Then the clockmakers have almost an hour to get cracking with maintenance.

At the new midnight exactly the giant hands are started once more, but the clock stays dark and utterly silent. Finally, a bit before 2am, the chimes and strike are set going again, and the lights go back on. All this happens with military precision, and Big Ben will have been put in apple-pie order for another six months.

“If you’d told me when I was growing up in the East End that one day I’d be looking after the most famous clock in the world,” Roberson says, “I wouldn’t have believed it. Being a clockmaker is a fantastic career, I wouldn’t change this job for anything.” He then adds with a laugh: “Don’t tell this lot, but I would have done it for nothing!”

BIG BEN FACTS

• Big Ben first chimed in the clock tower in 1859. The clock mechanism that operates it weighs five tonnes and is about 15ft across.
• Originally cast in Stockton-on-Tees, the 16-tonne bell, Big Ben, was put on show, but broke when the massive 13 hundred-weight (about 586 kg) hammer struck it. Recast in 1858 at the Whitechapel Bell Foundry, E1, the bell was installed in the clock tower, now renamed the Elizabeth Tower, with a lighter (200kg) hammer, but still cracked four months later; however, that small crack was successfully patched, and adds to the bell’s unforgettable tone.
• Big Ben, and the four “quarter bells” that ring just before it, is run by one of the oldest and most accurate mechanical clocks in the world.
• The sound produces 114 decibels and the clockmakers wear ear defenders. 
• Find out more from British Watch and Clockmakers’ Guild