Police patrolled the grounds of Blenheim Palace and neighbouring streets yesterday to thwart a planned Fathers 4 Justice protest.

Officers descended on the 18th century stately home and its 2,000 acres of parkland after a tip-off the campaign group was planning a St George's Day publicity stunt.

Palace staff were also put on high alert.

Ch Insp Dennis Evernden, West Oxfordshire police chief, said last night: "We had intelligence to suggest that Fathers 4 Justice may have been preparing for some publicity stunt to coincide with St George's Day, with Blenheim Palace as the venue.

"We worked in partnership with Blenheim Estates so should any activity take place we were in a position to ensure the health, safety and welfare of their staff and the public visiting."

But with a police van parked outside The Star pub, where protesters were believed to be planning to meet, and officers patrolling the area, no-one showed.

The suspected protest was thought to have been part of a wider St George's Day campaign by the group, with other stunts planned in Scotland and near Bristol.

But it is thought the group decided to call off the protest after a newspaper ran a story about the plans.

Mr Evernden said he did not know why the protest failed to happen.

He said: "The police presence and the increased security from Blenheim Palace themselves may have deterred them, or they may have thought it was a wet morning and decided not to come."

An email purporting to be from the group and obtained by the Oxford Mail said: "We need your support urgently.

"Several brave Fathers 4 Justice activists will be in action at Blenheim Palace, home of Winston Churchill, and this will be a significant protest.

"Protesters and dress code theme will be St George, Winston Churchill and English flags.

"We are in our own Battle of Britain, the UK is in breakdown - family breakdown - the devastating effects of this can be seen on every street corner; young offending, drug taking, violent crime and welfare dependency.

"We must force the family courts in London to establish a legal presumption to contact between children and their parents."

The group was founded in December 2002 as a campaign group aiming for reform in family law.

Members have powder-bombed former Prime Minister Tony Blair in the House of Commons, scaled the balcony at Buckingham Palace in a Batman costume, invaded the pulpit at York Minster during a General Synod service and taken the live National Lottery Draw off air.

Its officials temporarily suspended operation in January 2006 after a splinter group was accused of plotting to kidnap Tony Blair's son.