Donald Trump is reportedly keen to ride in the Queen's state carriage
According to officials, the President views the carriage procession to be an important part of his itinerary for his scheduled visit in October.
But police sources are said to be concerned about the security of the procession amid fears of anti–Trump protests that may erupt during his visit.
Former President Barack Obama travelled in an armoured motorcade, protected in a bullet and bomb-proof car, during his state visit in 2011.
Donald Trump is set to visit the UK in the second week of October
A source within the Metropolitan Police told The Times: "The vehicle which carries the President of the United States is a spectacular vehicle. It is designed to withstand a massive attack, like a low-level rocket grenade.
"If he's in that vehicle he is incredibly well protected and on top of that it can travel at enormous speed. If he is in a golden coach being dragged up the Mall by a couple of horses, the risk factor is dramatically increased.
"There may well be protections in that coach such as bulletproof glass, but they are limited. In particular it is very flimsy."
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First Lady Melania Trump who is married to the 45th President of the United States, Donald Trump.
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If he is in a golden coach being dragged up the Mall by a couple of horses, the risk factor is dramatically increased
Prior to the President's inauguration, Conservative backbencher Jacob Rees-Mogg told the Express.co.uk it was likely that Mr Trump would get to use the royal carriage.
He said: “There are no second-tier state visits. If you come on a state visit you go for a ride in a carriage with the Queen, you get invited to a state dinner, you get to stay in Buckingham Palace or Windsor Castle and the protective guard turns out to be inspected by you."
The Met will reportedly liaise closely with the President’s secret service to plan the event.
Protesters in London over the proposed state visit earlier this year
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Queen Elizabeth II making her Royal visits in her many colourful and elegant outfits.
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Queen Elizabeth II meets residents at Priory View, an independent living scheme for older residents, in Dunstable as part of a visit to Bedfordshire
Hundreds of heavily armed agents are also expected to travel with Mr Trump.
The security concerns come as tensions have escalated between the US and North Korea after Kim Jong-un’s chiefs attempted a missile launch on Saturday night (Sunday morning, local time).
Earlier this year, anti-Trump protests erupted across Britain following the President’s inauguration in January.