Fourteen(14)-Vehicle Convoy Accompanies Donald Trump Through Britain's Streets - PHOTO

From an uninvited hand reaching for his car door handle to a full-blown nuclear assault, Donald Trump was ready for anything as he began his visit to Britain yesterday.

He was protected by thousands of Metropolitan Police officers in a £25million security operation, as well as hundreds of his own secret service agents.

One of the most visible elements of the effort to protect the US President was the 14-strong motorcade that took him from Buckingham Palace to Westminster Abbey after he had flown in earlier by helicopter to meet the Queen.

At its heart was 'The Beast', the heavily modified £1.1million Cadillac with 5in-thick bulletproof windows in which Mr Trump travels. 
 
Encased in ballistic armour and weighing around nine tons, it contains a sealed cabin with an independent oxygen supply and bags of blood matching the president's type in case of a medical emergency.

Should anyone grab the door handles without authorisation, a 120-volt shock can be delivered at the flick of a switch. The car can also emit tear gas and flood the road with nails or an oil slick. Flanked by nine Metropolitan Police motorcycle outriders, the convoy also included a decoy version of The Beast, a black SUV carrying heavily armed close protection agents and a vehicle with members of the Secret Service's elite counter-assault team, equipped with everything from night vision goggles and concussion grenades to heavy body armour.

A vehicle towards the back of the fleet carried the 'hazardous materials mitigation unit', with sensors to detect nuclear, biological or chemical weapons attacks and the gear to respond to them.

The convoy also includes a satellite communications system that allows the President to send and receive messages on the Pentagon's secure network, even in the event of nuclear war. Another vehicle can jam signals that could detonate bombs remotely.

The motorcade also carries Mr Trump's doctor and a senior military aide with a satchel known as the 'football', containing nuclear missile launch codes.The astonishing fleet of cars, as well as armoured aircraft, were flown in from America before the visit. A number of them, including The Beast, were seen filling up at a petrol station in London on Sunday.

At Winfield House, the US Ambassador's residence where the President and his wife Melania are staying, elite counter-sniper secret service agents were seen on the roof.

Metropolitan Police firearms and counter-terror officers are also working to secure the capital, where as many as 250,000 anti-Trump protesters are expected today.

Mr and Mrs Trump flew in to Stansted Airport in Essex on the presidential aircraft Air Force One around 9am yesterday. 

From the airport, they were flown to Winfield House in Marine One, a name referring to any Marine Corps aircraft carrying the President.

Later they flew from the residence, on the edge of Regent's Park, to Buckingham Palace on the same helicopter, a VH-3D Sea King.

The Metropolitan Police said it was too early to say how much the 'multi-agency policing operation' would cost but it would be 'significant'. Estimates have put the total British policing bill as high as £25million.