Clock watch for Big Ben

For nearly a century and a half Big Ben has told Londoners the time. More than just a famous landmark, its chimes have become a symbol of time itself.

But now it could be about to grind to a halt. A dispute between the Palace of Westminster and the men who look after it means that the very reliability of Britain's most famous clock is under threat for the first time in decades.

That danger comes to a head this weekend when the clocks go forward and the craftsmen who check the cogs, grease the bearings and generally keep it going, are meant to be giving Big Ben its twiceyearly overhaul.

But a dispute between the firm which maintains Big Ben - Thwaites & Reed, the world's oldest clockmakers - and the Sergeantsat-Arms who oversee the day-to-day management of Westminster, means the essential overhaul might not go ahead after all.

If that happens, a trade dispute might achieve what the Luftwaffe failed to do and stop Big Ben.

Big Ben's proud record for reliability exists despite the fact that the experts only gain access when the clocks go forward to British summer time and back to Greenwich Meantime-each autumn. It has not had a major overhaul since 1956. However Hastings-based Thwaites & Reed has dramatically terminated its contract to wind and maintain the Great Clock inside Big Ben and 2,000 other timepieces at Westminster, saying it was losing £1,000 a week.

The company says its attempts to renegotiate the contract were "arrogantly rebuffed" by Westminster officials. Melvyn Lee, the director who has overseen all maintenance work, claims no one else has the expertise and knowledge to ensure the Great Clock remains in working order. He says there is a "very real possibility" the clock could stop unless vital maintenance work is carried out.

Mr Lee said: "It's an old clock and has developed latent fractures. It's old metal and is under great stress. We know all the parts and what to look at for potential problems.

"It's been 30 years since anyone outside of Thwaites& Reed has handled the Great Clock and any maintenance work carried out by other people is unlikely to be thorough enough. We didn't want to end our association with the clock as it's an icon for London and Britain, but the stance of the Palace has left us with no choice."

In retaliation, the Palace of Westminster said it had recruited the firm's two expert clockmakers to ensure work is done on time. A spokeswoman said it had been put in a "difficult situation" and used legislation governing public services to meet its obligation to keep the clock working. She added: "The two men are employees of the House."

Mr Lee says the men's contracts stipulate they cannot work at the Palace of Westminster for three months after leaving. He adds: "We've had rivals lure away our staff in the past so this clause was put into the contract to prevent it happening again. We will consider legal action if they insist on trying to take our staff. It is unacceptable, bullying behaviour."

The clock last stopped in 1976 when a part broke and the weights that allow the handles to turn plummeted to the bottom of the tower. This weekend its hands will be stopped at 10pm and the lights dimmed before two hours of work is carried out.

Big Ben is probably named after either the 25-stone Welshman Sir Benjamin Hall, first Commissioner of Works at Westminster, or the boxer and local pub landlord, 18-stone Ben Caunt.

The arch-shaped vents around the tower top were a Victorian attempt to release sewage gases from the Houses of Parliament.

A third of the way up the tower is a prison cell for MPs in breach of parliamentary privilege.

The tips of the copper-sheet minute hands travel 118 miles a year.

Big Ben can be heard up to four and a half miles away.

During the Second World War a bomb hit the House of Commons, temporarily knocking 90 seconds off the clock's accuracy.