London 2012: Securing the heads of state
London 2012 - sporting spectacle, international showcase, cultural occasion. All this and likely the largest gathering of heads of state and leaders of countries ever in the UK.
Ninety-five of them will be in the Olympic Park to watch the opening ceremony - ranging from the prime minister of Russia through to the president of Mongolia to the grand duke of Luxembourg.
While it is a unique situation which provides a chance to show London off to the great, the good and the perhaps not-so-good, it also presents significant logistical and security challenges.
The Foreign Office has an international dignitary management team in charge and a protocol co-ordination centre in Canary Wharf to oversee the whole process.
Each leader is assigned a visitor liaison officer for the duration of the Games. In all, 120 have been trained - although no-one can be sure exactly which leaders will or will not turn up until they actually make it. Heads of state have not been invited by the government but by their own national Olympic committees.
Some are expected to miss the opening ceremony but appear for a particular sport (President Putin of Russia for the judo, perhaps).
The teams work closely with Transport for London and Games organisers Locog to make sure all the transport logistics are in place, so that a leader gets whisked around the capital without delay.
Transport to the opening ceremony, however, is a little less flash.
Coaches, officials say, are the most effective way of getting all the leaders there and the method used in recent Games. The potential pitfalls of the seating arrangements, however, boggle the mind.
There are protocol rules for who can sit with whom and "sensitivities'" are managed, although officials decline to elaborate on exactly how.
One assumes this means it will not be the type of free-for-all, first-come-first-served boarding process that we have all come to enjoy on budget airline flights. Also that it will perhaps not be like school bus trips in which the "cool kids" try and bag the back seats so that they can cause trouble.
North Korea's new leader is not attending, perhaps unsurprisingly, and also perhaps to the relief of the organisers who will not have to worry about getting his country's flag confused with that of South Korea (whose leader is also not in town) - as happened to the women's football team.
At the stadium, more protocol kicks in. Technically all leaders are supposed to be treated equally.
'Air-traffic control plan'
They enter the stadium the same way as athletes - Greeks first, then the hosts, then the others in alphabetical order.
It is the visitor liaison officers who are responsible for making sure the leaders get to where they are meant to be on time.
If a head of state suddenly needs to change their itinerary, the officers - in conjunction with the team at Canary Wharf - will do their best to make it happen.
One wonders if among the scenarios the Foreign Office says it has planned for is the possibility of multiple leaders bumping into each other at the perfume counter at Harrods and, if so, whether they have worked out the protocol for who goes first.
An official describes the overall operation as like a huge air-traffic control plan - all of which has to be undertaken in conjunction with the embassies keen to make sure their leader gets the right treatment.
The Olympics are a time for so-called "bilaterals" or meetings between leaders to take place. The Foreign Office says it has a busy programme with Foreign Secretary William Hague meeting half a dozen foreign officials either side of the opening ceremony. Other countries will also be free to organise their own talks (at department stores or embassies).
Of course security is a real issue, with not just terrorism but also protesters seeking to make a point against one government or other.
Some countries, as officials put it, also import threats with them. The Metropolitan Police's Special Operations Command is in charge of looking after the VIPs. Its protection officers and outriders will be on hand to keep away protesters or more serious threats.
Countries are allowed to bring in their own security, but the UK has to agree the plan and police need to be content there will be no interference with their own operations.
The largest security operation comes, unsurprisingly, from the United States.
The US Secret Service is charged with protecting Michelle Obama, whose movements today alone include a breakfast at the University of East London, an event to promote healthy living, and the Queen's welcoming reception for heads of state at Buckingham Palace. All that before the opening ceremony.
But there is a much wider US contribution to Games security.
In testimony before Congress on Wednesday, the director of the National Counterterrorism Center said that a "threat integration center" had been established to "operate round the clock providing real-time situational awareness and threat analysis". This is believed to be housed within the US Embassy in Grosvenor Square.
In the run-up to the Games there have been regular briefings by the Security Service MI5 and other agencies to visiting countries, although inevitably some receive more attention than others.
One of the biggest official delegations is of course from Brazil. Rio is hosting the Games next and is watching closely to see how London does it all.