A raised tunnel to protect the Prime Minister and other delegates at the Labour Party conference was gingerly lowered into place last night.

The bridge will be guarded by police and will allow politicians to walk safely between the Brighton Centre and hotels and cut the number of security checks.

The 15-metre, four tonne structure was brought from Coventry and installed above Cannon Place, linking the Hilton Metropole and Russell Road car park behind The Grand.

Cannon Place was closed as a crane lifted the steel and timber bridge with chains and slotted it into metal stilts on either end.

A hole was knocked into the exhibition hall at the Metropole to create a door and a wheelchair lift will also be fitted.

Construction manager Nigel Crane said: "It is a very unusual structure as regards conferences and exhibitions. It slotted into place first time, which is quite unusual in construction, but it had been very precisely measured."

The idea is to allow delegates the freedom to roam between the Brighton Centre on the seafront, where the conference will start on September 24, and the Metropole and Grand hotels.

The bridge, paid for by the Home Office, means Russell Road and Canon Place can be kept open to traffic.