An accident on the A34 north of Oxford has now been cleared, which should ease traffic heading for the CLA game fair, according to police.

Traffic was gridlocked this morning as thousands of drivers headed for the CLA Game Fair at Blenheim Palace in Woodstock.

During the rush-hour, traffic was at a standstill on the A44 approaching Woodstock, and an accident on A34 northbound just after the Peartree interchange added to the congestion.

One car overturned about 8.30am. Claire Gourlay, a spokesman for Oxford Police, said: "The driver was fine and did not need any treatment from paramedics.

"The vehicle was recovered shortly after 10am and the northbound carriageway is now open."

Drivers also faced delays on the A420 and A40 and Stuart Thompson, a spokesman for the Highways Agency, said: "The incident on the A34 contributed to the traffic delays."

Royalty and celebrities are joining the expected 138,000 visitors descending on the palace for the 50th anniversary Game Fair.

The event, which continues over the weekend, is the world's biggest sports exhibition and the national event for 50,000 owners of rural properties represented by the Country Landowners' Association.

Tomorrow, the Duke of Edinburgh will be popping in to tour the show and also present long service awards to gamekeepers.

Among the many celebrities expected to attend are Elaine Page and Bernard Cribbins, who have set their sights on raising money for The Children's Trust in a charity clay pigeon shoot.