CLA Game Fair organisers were last night reviewing traffic plans in a bid to avoid a repeat of jams which clogged roads yesterday.

Tens of thousands headed to the world's biggest game fair at Blenheim Palace from early morning.

But gridlock caused delays for thousands of commuters and left many wondering why more had not been done to avoid the delays.

West Oxfordshire District Council, police and the fair organisers said efforts were being made to resolve the situation before thousands of other drivers head to the event today and tomorrow.

Kidlington resident Clive Walsh, 50, a BT engineer, said: "I tried to get into Oxford, but in the end I had to give up.

"This debacle seems to happen every time there is a game fair and they need to get the traffic management right. The road network has been at a standstill."

In 2004, when the event was last held at Blenheim, drivers experienced similar problems after a truck laden with thousands of hens overturned.

This year Royalty and celebrities are joining the expected 138,000 visitors to the fair.

Sam Simpson, West Oxfordshire District Council spokesman, said efforts had been made to minimise problems.

She said: "We have every empathy with drivers who have been delayed in the congestion and would like to assure people that every effort is being made by the CLA and the West Oxfordshire Safety Advisory Group, which includes police and local authorities, to resolve the situation.

"While traffic planning has taken place over the past 18 months in preparation for the fair, the volume of traffic yesterday morning on the main routes affected was unprecedented."

The combination of thousands of drivers heading to Blenheim, and an overturned vehicle on the A34 north of the Peartree interchange, led to lengthy tailbacks on the A44, A34, A420 and A40.

The crash happened at 8.30am, with the vehicle cleared from the carriageway by 10am, but traffic delays lasted until early afternoon.

Paul Stockwell said: "I was stuck in the traffic round Oxford, so had to call off an important job interview as I could not get there.

"The organisers of this game fair and the police have some explaining to do.

"I now have to explain this to the Jobcentre and have lost half a tank of fuel - expensive when you are on £60 a week."

Signs in and around Woodstock were put up a month ago warning local traffic about the fair, and routes were set up to ensure as little disruption as possible in Woodstock and Bladon.

David Hough, game fair director, said yesterday thorough traffic planning was hampered by exceptional circumstances, including the rush-hour accident.

He said a helicopter was used to activate electronic diversion signs positioned on approach roads.

He added: "There were 40,000 people here today (Friday) and the situation at the weekend will be much better - with no rush-hour there will be 25 per cent less traffic."

Mr Hough said traffic was directed away from Bladon and Woodstock.

Visitors to the fair were asked to enter the estate through the Ditchley Gate, or park in fields off the Bladon roundabout to avoid congestion on the main road through Woodstock.

Ms Simpson added: "A traffic monitoring system in place at the game fair, which included a helicopter, enabled back-up traffic plans to be put in place.

"However, this forced traffic, which should have continued north on the A34, to meet traffic coming from the Witney direction, causing further congestion in that area.

"Over the weekend, all parties involved in traffic planning will be reviewing the situation to ensure good traffic flow."

She added weekend traffic was expected to be lighter, and fair visitors spread over a longer period.