In the dangerous world in which we now live, the staff responsible for the travel advice put out by the Foreign Office have a thankless task. They are pilloried if they create the impression that nowhere is safe to visit, and damned if they fail to warn of the risk of a fatal attack. So they try their best to steer a course that conveys an appropriate sense of caution. Tragically, some of their Consular Department colleagues - who, unlike most of us, cannot choose whether to stay or leave a country when risks increase - died in Istanbul on Thursday.
Even after last Saturday's murderous attacks on two synagogues in Turkey's largest city, which followed a series of bombings on UK and US targets in Istanbul over the summer, the Travel Advice Unit stopped well short of advising against visits to the city. Only after the bombing of HSBC and the British Consulate did it declare, "There is a high threat from terrorism in Turkey" and advise against "all but the most essential travel to Istanbul".
"There's absolutely no political or economic motivation behind travel advice," the director of consular services for the Foreign Office told me before Thursday's outrage. "We see it as a purely pragmatic, practical assessment based on all sorts of information we have of the risks concerned," said Paul Sizeland, who took over the job in the summer.
Certainly, the breadth and depth of official travel advice has been transformed in the past five years from the usually curt and anodyne summaries that provided less useful information than you would glean from listening to the BBC World Service for half an hour. The Consular Department has also promoted the need for greater cultural sensitivity among British holidaymakers abroad. But there is evidence that the official line on the risks facing travellers is more positive for "friendly" countries than for nations to whom the UK government is indifferent or hostile.
Take the advice on the US, the country that we are given to understand is our closest ally. Some of the warnings about travel in America made by the Foreign Office are given below in Something to Declare. But the summary of the FO's advice concludes, "The US is a hugely popular destination for British travellers."
Why is that odd? Because I have searched the official travel advice for destinations that are even more "hugely popular" among UK travellers than America, such as Italy and Spain, and have found no similar robust official endorsement of their tourist potential. France, our favourite overseas destination, rates only the observation that "the vast majority of visits to France are trouble-free".
Then there is the case of Indonesia, which has been off-limits since the Bali bombing 13 months ago. The capital, Jakarta, has endured a recent history of bomb attacks similar to those in Istanbul, with a slightly lower loss of life. "We continue to receive information that indicates terrorists are planning further attacks, including against Westerners, throughout the country," warns the Foreign Office.
You or I cannot argue with that, nor are we ever likely to be privy to the intelligence sources the FO uses. Yet evidence in the public domain suggests the sensitivities of friendly governments are taken into account when formulating travel advice.
In the Nineties, Egypt suffered a sequence of terrorist attacks that deliberately targeted foreign tourists, culminating in the massacre in Luxor in 1997 that killed more than 60 visitors. But at no stage were British travellers advised not to go. Conversely, during some political instability in Argentina - mild, by the standards of South America - UK visitors were warned off by the Foreign Office.
On a planet where Britain looks seriously short of friends, it looks to me that the path that officials feel they must steer is a tortuous one. Mr Sizeland refutes this view: "It's obviously a pity, and causes damage to local economies, when travel advisories have the result of reducing tourism activity, but our paramount concern has to be the safety of the British traveller. At the end of the day, the buck stops with us."
November 20 will take its place on the calendar of outrage along with September 11 and October 12, the day of the Bali bombing in 2002. The grief of the families who lost loved ones in each of those attacks is immeasurable; and the human cost of Thursday's blasts, like that of the earlier attacks, will reverberate far beyond their suffering.
Thousands of other families will lose their livelihoods as a direct result of the attacks. They are the overwhelmingly generous, hospitable and friendly Turkish people who work in tourism, and whose jobs will simply be wiped out by an immediate and precipitous drop in visitor numbers.
Istanbul is one of the world's greatest cities, a gracious and intensely human place full of small kindnesses. Yet it will be erased from the travelling public's wish-list of destinations for years. Anyone who wants to see the Agia Sophia or Blue Mosque in solitude will be able to do so, and the restaurateurs on Galati Bridge will be very pleased to see you.
THE EFFECTS on holiday resorts elsewhere in Turkey are more difficult to quantify. The country has long offered cheap and cheerful beach holidays, and has maintained a fairly strong tourist industry despite the threat to tourists posed by the Kurdish separatist group, the PKK. But the horrific images of carnage in the country's largest city may persuade many to go somewhere they perceive as safer, on the basis that the family holiday should be kept as far away as possible from international terrorism.
Tourism workers all along the coast from Alanya to Bodrum will be poorer as a result. Such considerations were unlikely to have been at the forefront of the contorted minds of the perpetrators of Thursday's appalling massacre in Istanbul. Where will British holidaymakers go? Probably back to Croatia, which is just returning from its spell in the unhappy cycle of unpopularity.
Travel for most of us is a discretionary activity, and anyone subscribing to a generalised notion that the planet is becoming more dangerous can simply stay at home. Millions will: they, and the planet, will be poorer as a result.
British travellers will not necessarily trade in their weekends in Venice or Barcelona for a weekend in Wales, though; the evidence is that people will substitute overseas travel for a trip to the theatre or a spot of work on the house, just as - over the past few years - they have replaced drama and DIY with short breaks to the Continent. The publicans of Prague, who have become accustomed to free-spending weekenders from all over the UK, may face some quiet nights - and the meagre margins that many in the outbound travel market have to survive on will get even thinner.
Britain's tourism industry will suffer, too. Many prospective visitors to the UK will doubtless change their plans as a result of our elevation to the top of terrorists' hit-list. With 200 nations vying for travellers' hearts and wallets, they will reason, why go to a nation so visibly under threat. The consequent loss in revenue and jobs of those working in UK tourism needs to be added to the cost of the Iraq adventure.
A bleak postscript to Thursday's attack, on the Foreign Office website (www.fco.gov.uk/travel), reads, "Until further notice, the British Consulate in Istanbul will not be able to provide the full range of services." The physical and organizational wreckage may be repaired within months, but the human damage will endure much longer in this sad century.
The Foreign Office has issued a number for people to call for information about those who may have been involved in the blasts: 020-7008 0000Reuse content