Big Ben: Behind the clock face

On Sunday, the clocks go forwards. There are about 2,000 of them in the Houses of Parliament, among them Big Ben. This represents a logistical challenge, possibly a nightmare. Enter a small group of timepiece fanatics known as the clockmakers of Westminster. In lieu of time travel, we joined them exactly one year ago, to find out what'll happen this weekend behind the world's most iconic clock face...

The story begins at 8.30pm, and the Keeper of the Great Clock just ate a huge chicken yakisoba. "Not a good idea before charging up 334 steps," Mike McCann says, holding his stomach and laughing. He looks upwards at the spiral staircase. "Beautiful," he sighs. "They knew how to build, those Victorians." Towards the summit of Pugin's clock tower he scuffs and enters the mechanism room, in which click and clack Big Ben's guts. Earlier, McCann's five-strong team buzzed through Parliament, changing 1,000 clocks. Tomorrow, another thousand. But tonight it's the turn of the big one.

At 2am the bells must announce British Summer Time. The deadline has never been missed, although McCann concedes that it has been close.

In the centre of the room is a great, many-cogged mechanical heart, sat on two lemon-yellow pillars 15ft apart. Visible through each of the narrow, arched windows is a segment of one of four clock faces, London's streetlights rinsing them amber. At 310kg, the pendulum is so heavy it continues to swoop, but the clock is stopped and the dial lights off – the hands have been rotated to midnight, at which time they will be restarted. At the heart's edge stands Ian Westworth, a commanding figure with a clipped beard; on it perches Paul Robeson, gripping a 10ft break shaft like a harpoon, helping to lower the weights that drive the clock. Both men have white hair. One of them only just made it to work.

"I nearly got arrested tonight," says Robeson. His voice sounds like a French horn dragged from the estuary: gently pealing and heavily Essex. "I was trying to cross the road and this policeman sent me round Parliament square. I walked along the edge of the barrier, in the road. This policeman shouts, ‘Get out the road.’ I sort of ignored him, and he shouts, Oi, you little prick. So I said, don't you call me a prick, you c***."

Laughter bursts around the room. "That would've been funny if you'd been nicked, " laughs McCann, the maintenance manager for the whole of the Palace.

Robeson is slim, has sad eyes set in a face with a crease for each of its 53 years. He turns back to his harpoon. "I had visions of me in the station."

Big Ben is a three-train clock – one drives the hands, another the hourly chimes, and the last controls the quarter-hourly chimes. Think of the trains as huge bobbins on their sides. Around each is wound steel wire, and at the given time they unravel, pulling on cables attached to the hammers that strike the bells.

"I'm about to run the second weight down," says Westworth, 50, into a walkie-talkie.

"Roger that," spurts the reply from Huw Smith, Westminster's third and final clockmaker. He is at ground level with a 50-year-old apprentice called Stephen White, watching the weights" 15-minute descent. Beneath where they stand are what McCann calls torpedoes, Victorian compressed air barrels that shoot politician's plop through the Palace's sewage system.

"I've got to ring the BBC to tell them the clocks have stopped," says McCann, and ducks out the room as White and Smith enter it. White has a toothy grin, a glass eye and a gold hoop in each ear. After school in Putney he trained for the army and was shot in the left eye. Twenty years ago, he became Westminster's in-house furniture delivery man. (He once took a rug to Maggie Thatcher — given the choice of Persian or Indian, she simply asked for the cheapest.) Three Palace workers were offered the chance to join the clock department. One had angina; another had a heart attack; White volunteered.

Smith, a former lorry driver from south Wales, has sparkling glasses and a sweat-film on his forehead. A wiry beard hides his mouth. After breaking his back at work, he expected to spend the rest of his life in a wheelchair; somebody suggested clock-making, a sedentary occupation. Doctors fixed his back. Even so, the 50-year-old became a "clockie", but not one without problems. "I'm not allowed a clock in my house. My missus hates clocks." He glances around the room. "She doesn't like the sound of ticking."

Robeson unplugs the quarter-train's break shaft from the mechanism; Smith and Westworth climb to the link room to hoist the fan attached to the other end of it. The room has a low, curved ceiling. "The Victorians were amazing engineers," says Westworth, negotiating its scaffold grid like someone from the Ministry of Silly Walks. "But they didn't schedule planned maintenance. I would've liked a higher ceiling." His wife texts to say she is watching CSI. The couple met during the Bosnian war – after leaving the army, Westworth drove aid vehicles there for three years. She was his local interpreter. "So romantic," sniffs Smith, wiping a dry eye. "She followed you."

Westworth pulls on a blue nylon rope, raising the fan. "No, she married someone else. But she was divorced, I got divorced. Then she moved to London, and we . . ." a dull thud and Robeson's muted voice sound through the floor. "That's the ceiling." They laugh, and tie the fan in position. In 1997, Westworth took a horology degree. Asked why, he frowns. "It was a job that I could do and go home every evening."

Back in the mechanism room, Robeson removes the old ratchet by whacking a length of wood with a mallet. Maintaining a clock whose accuracy was drop-jaw when built and still impressive looks oddly extempore. McCann grows tense, clears his throat frequently. "I don't like doing this," he says. A small fan on the workbench shakes its head from side to side. "It's not designed for it." On the wall behind him, black and white photographs show the destruction wreaked when the quarter-train break shaft broke, sending the 1.25-ton weight crashing to the floor and tearing the largest bobbin from its seat. "I don't like to look at that. It was a huge disaster."

The pressure mounts for Robeson, too. "Do you know what a ratchet is?" he asks, seriously. It regulates the fly fan, which controls the rate of descent of the weights, making the bells ring at the correct intervals. His eyes sparkle. "It's a little bit bigger than a mouse shit."

British clock-making is a trade in terminal decline, and Robeson is one of its remaining gems. For most, it is a second or third career, but in 1975 he went straight from school to train at Hackney Technical College. "It's a dream to get to Paul's standard," says White, leaning on the black-scaffold railing that surrounds the mechanism. "I don't think it'll happen in my lifetime. He's at the pinnacle of the trade. The other cool bit is that he's such a nice fella, and deadly funny."

"Mind me hand," booms Robeson, as the fan is lowered. Smith helps guide it into position. White extends his right arm fully, fans out his fingers, holds them there. The pose is striking; squeeze him into a leotard and he could be a ballerina.

McCann turns to me. "I'm afraid I'll kick you out after this. They get distracted." Can I just watch and stop asking questions? No. He leads me from the room and around the walkway that skirts the tower behind the seven-metre clock faces. Tapped, they sound like granny's windows: single-glazed, surprisingly delicate. Each is made from 312 pieces of nacreous glass.

The temperature drops as we climb to the belfry. McCann leaves, says he'll be back in a minute. At night, there are few visible stars above London. From heights such as this you realise why: they've all fallen from the sky, caught on lampposts, on cars, in office blocks, dandled by the Thames, spoked by the Millennium Wheel, circling the BT Tower. The effect is breathtaking, a sidereal fizz. Accessing Big Ben is tricky (foreign tourists are banned; British residents must write to their MP, and approval takes weeks), but the view warrants the struggle. Little wonder Peter Pan circled the belfry on his way to Neverland.

And little wonder so many people want to visit. Earlier, Robeson recalled a birthday group he escorted in 2009. As excited as kids in a toy shop, they were; it was a job to eject Stephen Fry, Jools Holland and Hugh Laurie, who turned fifty that day. Bill Gates has also been up. So has Alan Titchmarsh. The clockmakers all have Blue Peter badges from the time Helen Skelton visited. McCann returns. The road back to the mechanism room is paved with donuts and coffee, he says. I have neither. "Come on," he says.

Toilet breaks for the clockmakers of Westminster are 668 stairs away. Consequently, not only are there no donuts or coffee downstairs: there is no food, no drink. "A lavatory might be handy," admits Robeson. "They have looked at putting in a lift, but part of the romance of the job is that you've got to climb up."

"I'll tell you what," says Smith. "I'll use the lift, and you can carry on up the stairs, being romantic."

"They should have a lift where the weight of us going down winds the clock up. Mind you, if we all got in together we'd probably over-wind it. When they built the clock, they didn't realise the effort it would take. A team hand-wound it constantly. They came up with ideas to automate the winding. One was to put a ratchet on Westminster Bridge: the horse and carts would come over, and the bridge would wind the clock up."

After tonight's effort, Robeson and co will sleep in nearby accommodation, rising at sparrowfart (daybreak) to change another thousand clocks. "And you can guarantee Monday morning there'll be a phone call saying: you haven't done my bloody clock," says Robeson. "You think, give us a break. We're wearing matchsticks in our eyes by then. You're bound to miss the odd one." Ticked off already are David Cameron's, the Speaker's, those in the Commons chamber. "Some staff work here their whole lives without going in half the rooms we do," says Robeson.

What kind of clocks does the prime minister have? "This one, they gave him a rubbish clock," giggles Smith. As willing as they are to discuss clocks and motorbikes – they all love motorbikes, even Smith, who almost died after smashing into a lorry one night after work – so they are unwilling to discuss politics. "No, he has a nice natural wood grandfather clock, a brass crown clock and a log case."

"We wind them up every week," chirps Robeson. "You think if the clocks could talk... the things they must have overheard."

He checks his watch – 11pm, time to start the going train. The ticking is produced by the double three-legged gravity escapement, a revolutionary device designed by Edmund Beckett Denison, which keeps the clock accurate by compensating for outside pressure. They all pull on ear defenders. White has a pair done in faux leopard skin. Westworth presses a button near the doorway; the engine sputters to life; winding the bobbins begins. The same happens every Monday, Wednesday and Friday. However, the going train is still hand-wound. Robeson grips a handle in its centre and rotates it. After 30 turns, Westworth takes over. Next, it's White, then Smith.

Exertion over, the men watch the mechanism as if it were a television. Every 15 minutes they switch the motor off to allow the weights to drop, though the chimes remain disconnected till 2am. They began work at 7am this morning, and as the night draws on they grow quieter, sleepier. Around 12.30pm, Robeson comes back to life: "The Speaker's wife has put on Twitter that I'm up here." What, Mrs Bercow? "Yeah, Sally."

"First-name terms?" says Westworth.

"She's put: High-fives to my mate Paul the clockmaker currently up Big Ben."

"Does she realise it's more than just you?" says Westworth.

"She says she's only interested in the good-looking one, the one with more experience."

"The wrinkly old guy, you mean?"

Robeson laughs. "Bollocks," he says.

Over the next hour, yawns edge out badinage. Sat on one of the room's two church pews is White, his eyelids drooping. Next to him drops Robeson. They could be two friends awaiting a delayed plane in an airport lounge. "It's going to get loud for the last time now," Westworth says. Nobody moves. Fifteen minutes later he unlocks the chimes.

At 12.55am (GMT), Robeson shoves himself off the pew and telephones the speaking clock. He picks up a red stopwatch, a few moments pass, he clicks. In five minutes to the second it will be 2am (BST) and the hammers must strike. If the clock is fast or slow, the clockmakers alter the number of pre-decimal pennies sat atop the pendulum. Adding one increases its speed by two fifths of a second every 24 hours. On the pendulum tonight is 6d, a £5 coin commemorating Big Ben's 150th birthday, and a crown, presented in 1977 by Robin Cook, to mark the Queen's silver jubilee.

"About double our wages," says Westworth.

"I may have to censor that," says McCann. "What he said was: we are amply rewarded."

"In heaven," says Westworth.

Like a phoenix of brick and stone, this tower rose 25 years after the conflagration of 1834 that razed Westminster. And this pendulum, the height of two tall ladies, has swung ever since. Through the reigns of two queens and five kings it swung; through two world wars it swung, a symbol of endurance under the care of four friends. And "care" is the word. One snow-choked morning, with trains up the junction, Robeson trudged three hours to reach work. Had he not, Big Ben would have stopped. If there are problems with the clock, they take them home, to bed. They work weekends whenever necessary. "I do it at the drop of a hat," says Robeson. "I love coming here. I get a buzz every time. As soon as you come in this room you hear that slow ticking, as if it's alive. And you're the one giving it life." When she visited him at work, his wife felt it was like meeting the other woman.

Two minutes to go, and Westworth switches on the dial lights: first the west, then south, east, north.

Stopwatch in hand, Robeson climbs to the belfry. "You forget the eyes of the world are on you," he says, "oblivious to the thousands of people looking up. Then you come up here, look down, and realise. If you thought about it too much you'd panic." Outside in the cold, he announces 20 seconds to go, pulls on his ear defenders and stares at the 13.7-ton bell. His hair wobbles in the breeze. Sixty metres below, double-decker buses whisper across Westminster Bridge; police cars squeal around Parliament Square; drunken shouts, cold kisses, laughter. Robeson watches the hammer. "Five seconds," he says, without turning. Tick. Tick. Tick. Tick. Tick.