The PM's worst nightmare: green on royal blue

Why protection officers have been forced to adapt and improve

A Taliban spokesman claimed that the primary aim behind Friday's attack on the US compound alongside the British Camp Bastion was to kill Prince Harry, who arrived in Afghanistan last week for a four-month tour of duty. The Taliban would say that, wouldn't they? Nevertheless, American and, according to official reports, British troops, took part in the defence, killing 18 Taliban fighters.

This poses a real headache for the Prime Minister and the Chief of the Defence Staff, who took the final decision on Prince Harry's latest deployment. Prince Harry is deservedly popular among the British public despite, or even because of, his colourful antics. His determination to serve Queen and country on the front line is widely admired, as it is in every young man or woman who joins up. But his presence in Afghanistan will almost certainly encourageor inspire the Taliban to greater efforts.

The real nightmare is not that the Taliban will be able to break into the base and get to him or shoot down his helicopter. Both are less likely scenarios, notwithstanding Friday's attack. What must keep the Prime Minister awake at night, on top of his other worries, is the prospect of a green-on-blue (supposedly loyal Afghan security forces turning on allied soldiers) involving Prince Harry or his entourage – a green-on-royal-blue, to coin a phrase. Let's hope they thought about all of this before deciding to let him go.

As if those responsible for the protection of the Royal Family didn't have enough on their plates, a security angle has emerged from the topless duchess affair. There is some doubt about the place from which a photographer took pictures of the Duchess of Cambridge sunbathing topless. But the photographer certainly had line of sight on to her – from less than a mile.

Lee Harvey Oswald's shots at President Kennedy were fired from a distance of 81 metres using an Italian Second World War rifle. The Barret M82 sniper rifle, used by the IRA to great effect against the British army in South Armagh in the 1990s, is accurate to 1,800 metres (1.1 miles). British soldiers in Afghanistan have claimed kills at even greater distances – as have the Taliban, who have a tradition of accurate marksmanship.

The US Secret Service, charged with the protection of the president and other senior officials, are well aware of this. Which is why we saw great photos of President Obama being bear-hugged by a pizzeria owner in West Palm Beach last week but never, or very rarely, long-range photos of the Obamas on a private holiday. If the Secret Service cannot secure a location from view, they won't go. It's never a privacy issue – always a security one.

British VIP protection tends to concentrate on the close in threat from "nasties or nutters". Venues are also routinely swept by sniffer dogs for explosives. But given the range of modern weapons and the number of people in the world who know how to use them, protection officers need to change the way they carry out their security surveys. There is a silver lining, though – if a sniper can't see you, nor can the paparazzi.