Londoners can no longer rely on the bongs of Big Ben to synchronise their watches - because its chimes have become “temperamental”.
Parliament’s clocksmiths have admitted the famous bell within the Elizabeth Tower has been up to six seconds out in the past fortnight, causing interruption to BBC Radio 4 broadcasts that use the sound live.
Three dedicated clocksmiths at the Houses of Parliament have tried to remove weights from the pendulum, but they have been left baffled but what is causing the problem.
They have since said the Great Bell of the clock, which is 156 years old, just has “fits every now and then”.
Ian Westworth, one of the clocksmiths, told Radio 4's PM programme: "The error started building up and went slightly unnoticed over a weekend. You can't just wind the hands forward. You have to make a very gradual change by adding coins to speed the clock up or taking weight off to slow it back down again.
"We don't know why it happened. You're talking about a 156-year-old clock, it does have a little fit every now and then. It's a little temperamental.
"Imagine running your car for 24 hours a day, 365 days a year for the last 156 years."
Despite the best efforts by the team, altering the bell made the clock slow and Mr Westworth said they have been up to the top of tower most days trying to get it right.
He added: "Traditionally we have to go up three times a week to wind the clock.
"We phone up the speaking clock and at five minutes to the hour, start a stopwatch, go up to the belfry, stand by the bell and the hammer.
"As it strikes the bell we'll stop the stopwatch. We can tell if it's going slightly fast or slow.”
