In 1844, when the new buildings were already under way, Parliament passed a bill providing for the

George Airy, 1892
©TopFoto.co.uk/Ann Ronan Picture Library / HIP

incorporation of a clock tower. Architect Charles Barry initially invited just one clockmaker to submit a design for the tower, until an outcry from rival companies forced him to put the commission out to tender.

When George Airy, Astronomer Royal, was invited to formulate the requirements of the new clock, he suggested that “the first stroke of the hour bell should register the time, correct to within one second per day, and furthermore that it should telegraph its performance twice a day to Greenwich Observatory, where a record would be kept”.

Despite widespread scepticism in the trade as to whether such pinpoint accuracy could be achieved, Airy stood his ground. He was assisted in his work by the formidable Edmund Beckett Denison, a multi-talented barrister and keen (though amateur) horologist appointed by Parliament. When the clock-making trade failed to rise to the occasion, Denison produced his own design, which was then built by the firm EJ Dent and Co., and completed in 1854. This was five years before the tower itself was completed.

Not one to suffer fools gladly, Denison went on to design the bell itself as well. A first protoype

The original bell breaks in the Palace yard
©TopFoto.co.uk/Fotomas

Big Ben, take two

Metal recycled from the first attempt went into the making of the second bell in 1858, which was made by George Mears at the Whitechapel foundry in east London. When finished, the bell was towed in triumphal procession through the capital on a trolley pulled by a team of garlanded horses. It was cheered all the way along the route to Westminster Bridge. Once installed, it chimed out the hour to Londoners for the very first time on May 31, 1859.

The tribulations of Big Ben were not quite over yet. Denison had insisted on fitting the bell with a striker more than twice the weight suggested by Mears. In July 1859, after barely two months of service, this oversized hammer succeeded in cracking the bell. It was to take another three years before a lighter, more appropriate one was fitted, though the bell itself was not replaced. It was rotated a little so that the new striker could hit an undamaged part of its surface, but the crack has never been repaired. If you listen carefully to the dong of the main bell as it strikes the hours, you can hear that the note it produces doesn’t ring entirely true.

Size and accuracy

The clock faces were designed by Augustus Pugin. Each one is 23 ft across. The minute hands are 14ft long, the hour hands 9ft, and the Roman-numeral figures are 2ft high. The tower presents its most spectacular face(s) when the clocks are illuminated at night. A light shining above the clock face tells you that Parliament is in evening session.

The accuracy of the tower’s timekeeping is guaranteed by the placing of a pile of old pre-decimal pennies on the pendulum. This ensures the clock can be relied on to tell the right time to the second even when the hands are laden with perching pigeons.

When you hear the chimes of Big Ben on the radio, announcing the 6pm news on Radio 4, for example, you are hearing no mere recording, but the real thing. A permanently installed live microphone relays the chimes via a link to Broadcasting House. So it was that on February 18, 1956, radio listeners also heard, in among the chimes, the conversation of a group of maintenance workers in the tower.