Mary Dejevsky: We love a national get-together. Can't we have more of them?

London must be one of the most routinely maligned cities in the world. Not by foreigners, who flock here in their excited millions, but by Britons – to whom it rightfully belongs. You can blame this on over-familiarity (its residents), on provincial chippiness (visitors from elsewhere), or on ingrained cynicism (a national failing, reinforced by the metropolitan media). You could also blame inertia – the natives just have not yet registered the cleaner air, cleaner streets, cleaned buildings and ubiquitous services – forgive, for a moment, the transport breakdowns – that are making London a destination to rival any world city.

Today the capital will be shown around the world at its radiant and verdant best, and it is guaranteed to look glorious even if it rains. Ceremonial London – the route the royal wedding procession will follow from Westminster Abbey to Buckingham Palace – has gained in resplendence by the day. Add the uniforms, the carriages, and colourful, cheering crowds, and – for the millions who choose to take part in person or as television viewers – this will be a joyous national experience. On the streets and buses yesterday, usually sullen, uncommunicative Britons exchanged laudatory comments with strangers about the look and feel of the city; there was an air of pride and universal goodwill.

The same exemplary organisation, the same washed and brushed streets and parks, the same crowds of enthusiastic natives – not forgetting the mix of new and familiar backdrops – should also make next year's London Olympics a resounding success. Even as the troops at Wellington Barracks were grooming their steeds and polishing their boots in preparation for the wedding rehearsal early on Wednesday, the Olympic Games website was stalling under the pressure of last-minute bookings, and had to stay open an hour beyond the midnight deadline.

Remember all those prophecies of doom ... Not only are the venues being completed on time and on budget, but nearly 2 million people, the vast majority British residents, applied for more than 20 million tickets between them, despite a system that meant they had essentially to gamble and commit money upfront. The opening ceremony was more than 10 times oversubscribed.

You might conclude that this testifies to the appetite of the British public for world-class sport – and, of course, it does. But it suggests something else as well: a desire on the part of very many people to be part of a great national event. For the truth is that, as a country, we have very few opportunities for collective national celebration. Even in the capital, the London Marathon provides almost the only regular mass event, when hundreds of thousands converge on the streets either to take part, or to urge the runners on.

Otherwise, there are the royal ceremonies, such as the Changing of the Guard, which the natives leave largely to the tourists, and the annual Trooping the Colour – for the Queen's official birthday – which no longer attracts a mass audience, if it ever did. You might consider Remembrance Sunday, when all branches of the state come together at the Cenotaph to commemorate the country's war dead, followed by a veterans' march-past. But this is far from being a festive occasion, and recent wars make itsocially divisive.

After that, you would be flailing to find a reason to consort and celebrate with your fellow countrymen. When you think about it, there is very little between a top-flight royal wedding or royal jubilee – essentially once-in-a-generation events – and the local farm show or village fete.

In London, Trafalgar Square is regularly corralled for cultural days and festivals, such as Chinese New Year or Diwali, and a River Festival celebrating the Thames is a recent innovation. But these are not national events by any definition. And with such a dearth of collective celebrations, anything really out of the ordinary draws enormous crowds. The parade of the Sultan's Elephant, a vast wooden edifice engineered by a French theatre troupe, completely paralysed the capital in 2006.

The fact is that we have nothing – no day, no event, no festival – that comes anywhere near the popular holidays such as Bastille Day in France or Independence Day in the United States – holidays that double as historical commemoration and mass national celebration. Bastille Day opens with a ceremonial military parade down the Champs-Elysées; it continues with a presidential broadcast and garden parties and it ends with fireworks, dinners and dancing in the streets. On Independence Day, every American of every age seems to be either marching in a parade or watching others marching; there are firework displays and barbecues – and much waving of the national flag. Both are inclusive national festivals that invite everyone, beyond colour and creed.

Is there not something to learn here? Our politicians' decade-long panic over Britishness has brought efforts to foster a sense of shared national identity by prescription. For new nationals, we now have the citizenship test, an oath of allegiance, and a requirement to prove competence in English. Perhaps, though, it is time to take another approach and capitalise on the proven appeal of the big national occasion.

The royal wedding has already demonstrated, in the anticipation, how starved the British are of opportunities to celebrate the very things that – still – define us beyond these shores: order and solidity; pageantry, civility, and an appreciation of how to do things "properly". Barring unpleasant surprises – though we are pretty good at keeping calm and carrying on – all these qualities will be in evidence today. Is it not a waste that they are brought out and dusted off but once in a generation? That there is not one day a year when our parks and landmarks are expected to look as ravishing as they do today? That the national flag lines the Mall more often for the benefit of foreign heads of state than for ours? We could revamp the Queen's official birthday; act on the proposal for Trafalgar Day, or create something entirely new. But let's do something. The enthusiasm for a mass national celebration will be obvious today on television screens around the world; it should not be allowed to pall.

m.dejevsky@independent.co.uk