The clock is renowned for its accuracy

and even survived a dozen attacks by Luftwaffe bombers during the Second World War,

continuing to mark the time within one and a half seconds of GMT .

It has, however been late on occasion .

In 1962 snow accumulation caused the clock to ring in the new year ten minutes late

and in 1976 the clock stopped when a piece of its machinery broke .

It also ground to a halt on April 30, 1997,

just 24 hours before the general election and once more three weeks later .

Big Ben is the name of the clock's 13-tonne bell,

which was named after Sir Benjamin Hall,

the British Commissioner of Works at the time of the clock's construction .

The official name for the Gothic tower in which Big Ben nestles is St Stephen's Tower .

Standing 100 metres (315ft) tall it was completed in 1858,

after an 1834 fire destroyed most of the Palace of Westminster.