Clocks in South London will have to go forward an extra nine minutes this weekend to 'realign' its time with the rest of the city.

South London homes and businesses are running nine minutes slower than clocks in Central and North London after a bureaucratic mix up, Mayor of London officials revealed today.

The Clock Tower at the Houses of Parliament in Westminster, often incorrectly called Big Ben, has been running 146 seconds a year faster than clocks in South London for the last four years, time experts have calculated.

A civil servant responsible for placing an old penny piece on top of the pendulum which powers the clock mechanism was inadvertently let go during Government cutbacks.

The small stack of old penny coins are used to adjust the time of the clock. Adding or removing a penny will change the clock's speed by 0.4 seconds per day.

Every year a penny is placed on top of the pendulum but when the axe fell on the Government's Department of Horology the man responsible for this job was made redundant.

Since changing the time on Big Ben could create global economic turmoil, the decision has been made to order all households in South London to recalibrate their clocks to fit in with the new time.

Businesses and homes must change all their clocks forward by nine minutes at 12 noon today or risk an on the spot fine of up to £100.

Mobile phone companies and computer firms have already been instructed to change all the times on their devices to fit in to the new time zone.

A spokesman for the Department of Horology said: "Changing Big Ben would create major problems in this country and arround the world. Big Ben is a symbol of time and it's bongs are relied on for the news not only on Radio 4 and the BBC but our World Service and shipping forecasts. The economic cost of moving Big Ben's hands by nine minutes could be up to £1.2bn.

"It is cheaper and easier for residents of south London stretching from Twickenham, Kingston, Wimbledon, Croydon, Sutton, Bromley across to Greenwich to change their clocks forward.

"We will be able to reset all the clocks to GMT in a few months when we enter saving time in Autumn.

"The problem is exacerbated in South London especially because some people travelling from South to North by train are actually arriving at their destination before they even left their departure station.

“It is embarrassing for everyone and among our timekeeping peers we have been made to look like fools.”

It is not the first time a country has altered its time zone for economic reasons. The island of Samoa jumped 24 hours into the future last New Year’s Eve, scrapping a day and altering the international dateline, so it can be on the same day as Australia, New Zealand and eastern Asia.