London's ambulance service is so concerned about the millennium bug it has built an entire duplicate control room in case its computers are disabled.

James Westhead: "The ambulance service fears communication systems will be strained at the millennium"

The service handles a hundred 999 calls every hour and says lives could be put at risk if it does not have a comprehensive back-up system.

Managers are also concerned that there will be a huge surge of calls from the public - up to ten times the average - during the millennium celebrations, which could overload communications systems.

It is vital that the ambulance service responds as fast as possible to emergencies. One estimate suggests that if response times are slowed by just ten per cent it could lead to an extra 30-40 deaths an hour.

Managers are determined not to repeat the experience of seven years ago when London's newly-installed call-handling computer system crashed.

Hundreds of emergencies went unanswered, and some patients died.

Among the people who suffered was Christine Dance, whose husband collapsed with a heart attack.

It took eight calls for an ambulance to arrive - two and half hours after her husband had died.

She said: "When I was ringing up it was so distressing. You could not believe this was really happening from a service you rely on."

With the millennium approaching, the service is taking no chances.

All computers have been purged of the millennium bug, and back-up telephone and power lines have been installed in triplicate.

The replica control room is at a secret location, with rows of identical computers and phone numbers.

In the event of catastrophe, the whole operation can be transferred in minutes.

Ian Tighe: Confident the system can cope

Ian Tighe, of the London Ambulance Service, said: "In terms of power we can survive, in terms of radio we can survive.

"But if we see telephone networks collapsing, then of course we would get no calls."

The ambulance service, however, believes its computers are millennium-bug free.