John Prescott: "We're going to get good transport benefits and integration"

The project was delayed by wrangling over the route, and financial problems.

Deputy Prime Minister John Prescott started construction at a "ground-breaking" ceremony on the banks of the River Medway where a new bridge will take the high speed link over the water.

But there is still a doubt over whether the £5.8bn link will be completed all the way into central London.

Eurostar journey will eventually be 35 minutes shorter

Stage one from the tunnel to the outskirts of London is due for completion in 2003, but Railtrack money for stage two - through the east of the capital to St Pancras station - is not yet guaranteed.

At the earliest it will all be finished by 2007 - 13 years after the tunnel opened.

Passengers should then be able to travel from London to Paris in two hours and 20 minutes - 35 minutes faster than current times.

Some say the damage to the countryside and the cost involved is a high price to pay for a little over half an hour, but Mr Prescott insists it is all worth it.

Prescott: "Good deal"

"We're going to get good transport benefits and integration, and we're going to increase the capacity for rail services in the south east," he said.

Then there were economic benefits with 8,000 working on the link and 50,000 eventually regenerating the area around the River Thames.

"I think it's a very good deal for the taxpayer," added Mr Prescott.

But critics say the deal has been struck at the expense of those living along the route.

Gary Thomas from the group North Downs Rail Concern said the project was being built on the cheap through the most populated route.

He told BBC Radio 5 Live: "The whole design philosophy all the way through has been 'What can we get away with it?' and never 'What's best?'."

He said a 3km tunnel to be built under the Downs was not enough, and believed the project was a waste of money which could be used on other rail projects.

"This line is absorbing all this money for such a little benefit," complained Mr Thomas.

The current service, he said was "slow through London and that's where the improvements should have taken place first".

Bernard Gambrill from Union Railways - the firm building the link - was confident the whole link would be built.

These Kent stables have to be vacated

"The financing plan is in place and has been accepted by government. The uncertainty is whether or not Railtrack will buy it," he told 5 Live.

Asked if the firm did not purchase the route, he said: "We will look for another buyer or we could even manage it ourselves."

The start of work coincides with a deadline for many landowners to vacate properties due to be demolished for the route.

One group of residents who need new homes are 49 horses.