PC Dave Hopkins, 41, had been riding five minutes ahead of the race, warning road users of the imminent arrival of the riders, when he was in collision with a car, receiving fatal injuries.
A member of the 35-strong Police National Escort Group, which is responsible for accompanying major cycle races, PC Hopkins, a father of four, was an experienced motorcycle escort rider, having worked on cycling events and royal visits.
News that a serious accident had occurred on the race route was relayed back to the main field just after it had raced through Worcester, 35 miles into the day's stage.
Officials stopped the race, and riders waited with their team cars while an ambulance and police went to the crash site.
Chris Boardman, Britain's number one rider, said: "The riders were as devastated as anyone and were happy to go along with the organisers' wishes.
"Any sport that involves speed has an element of risk to it," Boardman added. "Tragically, from time to time there are accidents and that is what happened today. All of us, riders and police, are volunteers and are here because we want to be here."
Fatalities are surprisingly rare in cycle racing, the last time a competitor died in a major British event was in the 1970s when a Czech rider was killed in the Milk Race. His death led the organisers and police to increase the size of the escort team.
Fabio Casartelli's death in the Tour de France three years ago was the first in the Tour since Tom Simpson collapsed and died on Mont Ventoux in 1967.
For many on the race yesterday, the incident revived memories of the Prutour's predecessor, the Kellogg's Tour, in 1994 when a motorist evaded the police escort and drove into a group of riders, injuring three of them. The sponsorship ended shortly afterwards and British cycling was without a flagship event until Prudential launched their event this year.
Yesterday's fatality, together with the incident on stage three when the field was sent off course, raised concerns that the new Tour's future might be endangered. However, Clare Salmon, the Pru's consumer marketing director, insisted that the company would stick to its contract and back the event for the next three years.
The Prutour will recommence today when the 90 riders left in the race will hope to rekindle some enthusiasm for the 91-miles stage from Bristol to Reading.
Yesterday's stint had been due to take in some severe climbs in South Wales which would have affected the overall standings decisively. Instead, racing resumes with 10 riders within 90 seconds of the overall leader, Stuart O'Grady, who should be capable of defending his advantage until Sunday's finale in Holborn, London.Reuse content