More than 500 different Transit models have been made by Ford

To mark the 40th birthday of the Ford Transit, 150 vans will set out from the Ford Dunton Research plant at Basildon.

They will make their way in three separate convoys to the QEII Bridge at the Dartford Crossing.

It coincides with planned works on the bridge, and the vans will have moved on by the time it reopens at 0830 BST.

The Backbone Cruise has been organised in part by the first Ford Transit Owners' Club, set up in 2005 as the van reaches its 40th anniversary.

Transit show

Recovery crews will be on hand in case any of the older vehicles experience problems.

Peter Evans from the Highways Agency said: "Drivers are advised that some of the vans may be travelling slowly as some of them date back as far as 1965."

The owners' club said the route from Dartford would follow the M25, the A26 and A27 through Kent and Sussex, and then the M27 into Southampton.

The whole convoy should have arrived at Ford's Southampton plant by 1200 BST at the latest.

Drivers will then be able to move on to a nearby Transit show with live music, food and drink and children's activities.

Ford Transit production moved to Southampton in 1971 and the four millionth vehicle was made in 2000.