Over 14,000 police officers will be on duty during the three-day visit by George W Bush.

The announcement that the number of police has been tripled came as a 61-year-old grandmother scaled the gates of Buckingham Palace to protest against the US president's trip.

The unprecedented security operation comes amid the twin threat of a terror attack and the prospect of large demonstrations against the president's policy on Iraq.

A new poll published today reveals that the majority of voters support the president's visit. Just over half of those surveyed by ICM for the Guardian said they welcomed the visit.

But over 60,000 demonstrators are expected in the Capital on Thursday in what will prove to be a complex policing operation for the Metropolitan force.

Other groups are planning a series of protests both in London and throughout the country.

Over 1,300 police are also set to be deployed in the prime minister's Sedgefield constituency ahead of the president's visit there on Friday.

Bush will arrive in the Capital tonight ahead of a formal welcoming ceremony tomorrow.