Inside the massive security operation for Trump's UK visit

There has been no expense spared for the UK's biggest security operation since the King's coronation.

This time the occasion is both royal and presidential. It is vast and honestly feels, well, American.

The operation has been led by Thames Valley Police, but officers from across the UK will also play a part in the visit. Windsor is a sea of fluorescent yellow jackets and black and white flat caps.

Officers are swarming the town and over the next couple of days will be sending drones into crowds, conducting boat patrols and deploying mounted units in and around the wider area. Authorities have planned for every eventuality but would not expand on whether the fatal shooting of Charlie Kirk had led them to heighten security measures.

The assassination of the US activist may have intensified consideration about potential threats, but authorities have had extensive security plans in the works for months. Operational firearms commander Sergeant Dan Hatfield explained that the police presence will be heightened - and every plan has been worked on in conjunction with the Secret Service.

"The residents of Windsor and visitors to Windsor are used to seeing a fairly high police presence, including armed police," Sgt Hatfield said. "However, for this state visit, they will see an increase in those numbers.

Fortunately, I've had experience working with the Americans with all the Secret Service. We have a really good working relationship and work fairly harmoniously together to ensure the safety of everyone involved." Whether in the air, on the ground or on the water, safety is paramount.

On a visit with the Thames Valley marine unit, Sky News witnessed what their 24-hour patrol of the waterways would look like. A section of the River Thames that borders the Castle will be closed off during the visit.

Sergeant Lyn Smith, head of the joint operations marine unit between the Thames Valley and Hampshire forces, said this is the biggest event she has worked on. "The team is highly trained, we are ready for anything that will happen on or around the water," she said.

"The marine support unit are going to be doing high visibility patrols, some searching, some specialist searching in and around the area, and working with our partners in the Environment Agency to deliver a safe event. "Similar to President Macron's state visit, we are still providing capability on the water, it's just on a larger scale for us." Read more:What we know about Trump's state visitWhat Trump's second state visit really means Notably, for the first time in any state visit or royal occasion, the section of the Long Walk leading up to the castle has been cordoned off with large white barricades erected to shield the residence from view.

Airspace over the town is also restricted for the duration of the visit, enforced using police drones and helicopters. Vehicles will be standing by close to patrol officers on the ground, holding their ballistic helmets, ballistic vests and shields if an incident occurs.

Thousands of protesters plan to descend on Windsor and central London during the visit to demonstrate against the president's trip. A rally in central London on Wednesday is expected to draw the largest crowd, but protesters from the Stop Trump Coalition have now confirmed plans for a Tuesday event too.

A royal welcome may not be extended by all - but many will be hoping they won't drown out the pomp for the president..