Identity parade: What do flags say about nations – and human nature?

So out it pops today, as always in the last week of April, waving in the wind like some great blowsy red-and-white spring blossom which has suddenly emerged: the Cross of St George. But while blossom is universally welcome, the red cross on white of England, hoisted in its homeland on this St George's Day, 23 April, arouses contradictory and dangerous emotions: enthusiasm on the one hand, contempt and distrust on the other. Can there be a national flag anywhere which is so potentially divisive in the very country it symbolises?

The reason of course, is simple, and troubling: in the last 60 years Britain has become multicultural, and for some people, especially on the far right, the Cross of St George, and indeed the Union Flag of Britain itself, have come to symbolise aggressively the white identity of the country pre-immigration; and so they have understandably become objects of suspicion to ethnic groups and the political left.

In recent years, however, the Cross of St George has made a comeback in terms of familiarity and acceptability, which most people date to Euro 96, the European football championships that were held in England that year. England fans adopted it when they played Scotland at Wembley, at a moment when waving the Union Flag seemed inappropriate (it contains the saltire, the Cross of St Andrew, and belongs to the Scots as much as the English) and from there it boomed. During the last World Cup, in 2006, the whole country was covered in red and white.

Some people worried about this; others took a quite different view, saying it was time to "reclaim the cross from the racists", and the opprobrium that once clung to the flag seems to have slackened. Whatever view you take, you had better be prepared for another explosion of red and white crosses this year, with the staging in June of the 2010 World Cup in South Africa.

Strange that a country's principal emblem should come to represent its divisions, when in virtually all of the rest of the world the national flag, at least ostensibly, stands for the union of the nation, and is respected as such. In England, by contrast and almost uniquely, there is very little flag respect; it has been replaced by flag distrust, which may be healthy democratically, but which has gone so far, especially on the radical left, as to make all flags seem suspicious to some, just as all nationalisms can seem suspicious. A few years ago a radical comedian wrote a piece on flags which finished with a paean of praise to flag-burners everywhere, encouraging the burning not just because protesters might disagree with something the country in question was doing, but because flags should be burned for being flags – "and flags are rubbish".

Well, maybe they are. Yet we can't get away from them. Ask yourself a question: if you were designing a country from scratch, one named after yourself, Great Smithia, perhaps, or Jonesland, would you ignore the idea of a national flag? You can be perverse and say "yes", but I bet you a pound to a pinch of snuff that in reality it would be one of the very first things you would think of, and you would agonise over it endlessly – does the red stripe appropriately represent my struggle? Do the green dots properly symbolise Auntie Maureen's Irish background? – just as much as you may have already agonised over your eight records for Desert Island Discs (for when you make it, and you finally get that call from the Beeb).

It's about who you are, and that can't be ignored. Emblems of identity are an essential part of being human. They have often been brightly coloured, down the centuries: think of the purple stripe on the Roman toga, the bright blue woad on the ancient Briton's face. In fact, such indicators are far older than humans, being hugely prominent in the natural world: think of the colours, and the colour patterns, in flowers, butterflies and birds, each belonging specifically to a particular species. Why do you think they're there?

Once upon a time the answer was that the Good Lord had put them there for our delectation. No longer. Now we know that, on the contrary, they have evolved as identity emblems with ruthlessly specific survival purposes, to attract pollinators, to win mates, to blend into backgrounds, to warn predators that you are poisonous; in short, to let you survive, and get your genes into the next generation (which evolutionary biologists would say was the principal purpose of existence).

Yet paradoxically, although they may be merely functional in their origin and purpose, colours in nature can also spark tremendous delight, tremendous elation in human spirits; and as someone who writes about the natural world and was pondering this paradox, I was led to flags, as a way of trying to understand how colours and combinations of colours affect us.

The point was, colours in nature had unconsciously evolved through the greatest of all designers, Natural Selection; but colours and colour combinations in flags, which in some ways were very similar, had been put there by human designers, quite consciously. How did they choose them? Why did they choose this one rather than that one? What was the trick? Did they have a secret, arcane knowledge of which colours would affect people in certain combinations, and why?

What's in a flag?

I decide to seek instruction in vexillology, which is the scholarly study of flags. (The word comes from vexillum, a banner carried by the Roman legions.) Vexillology is a sort of much younger brother of heraldry, the system of designing and registering knights' coats of arms which began in medieval Europe and still flourishes today. Heraldry, however, concerns itself with the emblems of individuals, or societies, or cities, but not with the flags of nations, largely because at its beginning, the nation-state was virtually unknown. But in the last century and a half, nation-states have sprung up across the world, from the unification of Italy in 1861 and Germany in 1871, to the plethora of new states in Africa, the Middle East and Asia which emerged from the old colonial regimes after the Second World War, and the new countries formed after the break-up of the Soviet Union. Now there are 192 member states of the United Nations, and though flags may indeed be rubbish, not one of these countries thinks it can do without one.

Vexillology as such came along a little more than 50 years ago, invented by a young American political scientist, Whitney Smith (he coined the term in 1958). Dr Smith is still a professional vexillologist, consultant, adviser and designer of flags, publishing The Flag Bulletin from his Flag Research Centre in Massachusetts. There was clearly a need for the concept, for the idea quickly caught on around the world, and 1967 saw the founding of the Fédération Internationale des Associations Vexillologiques (FIAV), which now does for flags what Fifa does for football or FIA does for motor racing. Organised vexillology was formally brought to Britain by William Crampton, a flag-mad-from-boyhood adult education organiser who met and corresponded with Whitney Smith and who in 1971, with Captain Edward Barraclough, the then editor of the standard British reference book, Flags of the World, founded the Flag Institute.

Considering it has been in existence for fewer than 40 years and it is no more, constitutionally, than a membership society of interested people, and has hardly any public profile, the Flag Institute has achieved a remarkable position of acceptance within the establishment in Britain; it is now principal advisor and designer of flags to Her Majesty's Government, and as such is more or less on a par with the College of Arms, the venerable governing body for heraldry, which was founded by Richard III in 1484. It is has a lot of naval links and is based in the Naval Club in Mayfair, and it is there I go to seek enlightenment from the institute's current chief vexillologist, Graham Bartram, and its president, Captain Malcolm Farrow.

Bartram, author of British Flags and Emblems ("Foreword by HRH The Duke of Edinburgh") is a cheerful,well-padded 46-year-old Scot, and probably now the leading vexillological expert – did you say that correctly first time? – in the country. He is someone the tabloids might label "Britain's Mister Flags". He has personally designed the flag of Tristan da Cunha, the flag of the Lord Warden of the Cinque Ports, a flag for Antarctica and the symbols of the UK Border Agency, among other various commissions. How does he go about deciding what he puts in a flag?

There were six basic guidelines, he says. The first is, keep it simple. "The flag should be simple enough that a child can draw it from memory." The second is to use meaningful symbolism: the colours or patterns should relate to what the flag symbolises.

The third is about colours: don't use too many. "Don't use eight colours; that doesn't work." There should be two or three, but no more, and they should be from the standard colour set, which is red, orange, yellow, green, light blue, dark blue, black and white, and to a lesser extent, purple. There's not much use for brown, or grey, or pink in the flag world. In fact, I ask him if he knows of any pink flag, and he responds instantly, with what I come to realise is encyclopaedic expertise: "The old flag of Newfoundland." I look it up later and there it is, a rather charming tricolour of green, white and rose, flown in the 19th century but now long fallen out of use. And very much an exception.

There is another important point about colours, Bartram says, which comes from the rules of heraldry: the difference between "metals", which are gold and silver, and by extension, yellow and white; and "colours", which take in everything else.

They should alternate. (The reason is to get contrast.) Metals should not be placed on, or next to, other metals; colours should not be placed on, or next to, other colours. The pattern should go, colour, metal, colour, as in most tricolours: red, white, blue; green, white, orange. Otherwise it won't work. "And the flag that proves the rule that it doesn't work is the flag of Cyprus, which is a gold island on a white background [metal on metal]. It's quite hard to tell what it is." I look it up, and I agree with him. Then an example of colour on colour which doesn't really work, he says, is the flag of Bangladesh, which is a red circle on a green background. I look that up too, and I agree again. "Neither of them work particularly well," Bartram says.

There is, however, an exception to the rule of don't-use-too-many-colours, one which does work, and one which he and Farrow, a retired naval officer who served in the Falklands, enthuse about, and that is the modern, post-apartheid flag of South Africa, the rainbow Y on its side, which is a specific heraldic device, a pall.

Designed in 1994 by the South African state herald, Fred Brownell, there are six colours in it: black, yellow, green, white, red and blue. It was meant to be a temporary flag for the first post-apartheid election, but it was so popular that Nelson Mandela kept it. "The South African flag breaks the rules – it has far too many colours in it, and logically, it shouldn't work, but it does," Bartram explains. "It sums up the country. It works culturally."

"It's completely unmistakable, and it achieves the main function of a flag, which is to be an identifying symbol," adds Farrow.

On that basis, they both enthuse about the flag of the United States. "The Stars and Stripes is a fantastic flag," says Bartram. "It's immediately obvious what it is." "It's terrific," chips in Farrow. "It's completely startling. It stands out against any background."

Standing out again a background is important, they say, which is one of the reasons why there was not a lot of green, for example, in flags in Europe, where the background itself is largely green: green trees, green hedges, green fields. In the Arab world, however, where the background is largely yellow – the sand of the desert – green is much more in evidence, and it reaches a climax in the flag of Libya, which is a plain green rectangle. And that's it. A tad on the boring side, perhaps? "It is the only national flag in the world with just one colour, and no design," Bartram says. "It's fine in Libya. But if you flew it in England, it would be invisible."

If you take an interest in flags, says Farrow, you begin to take an interest, not only in history and society, but in colour itself. "Red, yellow and orange are warm; blue and green are cooler. That's across the human race, not just in northern Europe. Greens and blues give a cooler feel. The sea is cooler than the desert; the trees are cooler than the rocks. That's not something learned from a book. It just comes from where you are."

Red, white and blue are the colours most commonly used in flags because of the terrific contrast they accord. The obvious example is the tricolour of France, supposedly created by the Marquis de Lafayette, commander of the National Guard during the French revolution, by bringing together the colours of Paris, which were red and blue, separated by the white of the French monarchy. Now tricolours, both vertical (France, Italy, Ireland, Belgium) and horizontal (Germany, Austria, The Netherlands, Spain, Russia), are among the most popular of all national flags, so much so that some are very similar: the horizontal red, yellow and green tricolour of Ghana is the flag of Ethiopia, upside down; while the blue, yellow and red vertical tricolours of Romania and Chad are, in fact, identical.

There are three more rules for designing flags, Bartram and Farrow explain. The fourth one is avoid using writing or lettering on the flag. This is because, unless the flag is double-sided, the lettering will be the wrong way round, seen from the the back; and not all of it might be visible when a flag flies, as it doesn't fly as a rectangle. "If you have a message saying Do Not Kill, a lot of the time it might actually read Do Kill," Bartram says.

The fifth flag guideline is, be distinctive; and the last one is, remember the wind. The design must remain recognisable both when rippling in a stiff breeze, and when hanging limply in still air.

The Cross of St George, it seems to me, fulfils all six conditions. It's simple: any child could draw it. It's meaningful: it carries the symbol of England's patron saint. It uses only two colours, red and white, a colour on a metal background. It's free from lettering. It's very distinctive. And you can always tell what it was, in a gale or in a calm.

Is that the reason why so many people respond to it? "Absolutely," believes Bartram. "It's a very clean, powerful, straightforward image." But he reminds me that even though the Cross of St George is something we associate with England, it belongs elsewhere too. It is the old flag of Montenegro, it is the flag of Genoa, and of Milan, and it is the basis of the flag of Georgia, where the red cross is surrounded by four more red crosses in each corner. Beyond that, it is found of the arms of numerous countries, provinces, cities and bodies who have St George as their patron, from Beirut to Barcelona, and from Aragon to Moscow. So if you see it today and you're one of those people who feel it's just the symbol for an exclusive national identity, you've got hold of the wrong end of the flagpole.