"WorldPride 2012 is going to be a unique occasion in a uniquely vibrant city, and I don't suppose we'll ever see its like again," says Paul Birrell, chairman of Pride London, the lesbian, gay, bisexual, transgender lobbying group, which opens the 2009 event this weekend.
"All we need now are lots of really interesting grass-roots ideas from a whole range of community groups to make this the best and most significant Pride fortnight the planet has ever seen."
Sandwiched between the Queen's Diamond Jubilee celebrations and the Olympic and Paralympic Games, WorldPride 2012 – a five-yearly extravaganza which uses high-profile parades and artistic events to highlight homophobia and Aids – will be staged in London almost three years to the day.
Although details of the event are at an early planning stage, a packed itinerary of theatre shows, debates, poetry, music and partying, culminating in the main parade through the streets of the capital, is expected to attract more than 1 million visitors.
"In terms of the sheer size and diversity of its LGBT scene, London rivals New York and San Francisco, but the fact we have fantastic venues such as Trafalgar Square and Piccadilly Circus on our doorstep gives us an in-built advantage over every other city I can think of," says Birrell.
"We're already talking to the Metropolitan Police about safety on the parade day itself, but when it comes to finalising other less spectacular events we need as many ideas from the community as possible," he adds.
This year's annual London Pride festival fortnight, which routinely attracts around 500,000 visitors, starts this weekend under the theme "Come Out to Play". Events include a series of Soho Gay walking tours, a Bad Film Club showing of Can't Stop The Music – the much-derided story of the Village People – and an appearance at the Southbank Centre by 4 Poofs and a Piano.
The route for this year's Saturday parade, which kicks off at 1pm on 4 July in Trafalgar Square, will include Oxford Street and Regent Street. Following the procession, there will be an afternoon of speakers and other events focusing on homophobia and discrimination against LGBT people.
While London Pride 2009 is likely to prove highly popular, Birrell is already also looking ahead to what he sees as the jewel in the Pride crown in three years' time. "Earning the right to host an event as culturally rich as WorldPride at a time when the world's eyes will already be on London because of the Olympics and the Diamond Jubilee is great for the LGBT community and great for UK tourism. It helps reinforce the message that there really will be only one place to be in the summer of 2012, and that's London."
WorldPride, which is organised by the umbrella group InterPride, has been staged only twice before – in Rome and Jerusalem.
While the organisers faced hostility from the Vatican in the run-up to WorldPride in Rome in 2000, visitor numbers to the city were boosted by at least a million. Jerusalem recorded a similar hike in visitors during the 2005/6 event.
While last year's behind-the-scenes bid by London Pride to host the WorldPride fortnight attracted far fewer headlines than that for the Olympic and Paralympic Games, the three-way pitch against co-finalists Stockholm and Brussels was "intense", says Martine Ainsworth-Wells, marketing director of the organisation Visit London.
"Along with Mayor Boris Johnson, we actively supported the WorldPride bid, because we believe it represents the kind of cultural diversity that keeps London as the world's foremost tourist destination, with five million visitors coming here annually," she says. "The fact that this event is being staged in 2012 will help ensure that the capital is in permanent carnival mode for the entire summer period that year, and I have no doubt that the Pride parade itself will once again be something that once seen is never forgotten."
While Pride events tend to attract attention for the sheer colour and audacity of their floats and costumes, London Pride festival director Shaun Newport points out that parties and parades are only part of the WorldPride message.
"We mustn't forget that Pride is a charity that aims to end homophobia or transphobia and the neglect of human rights as well as [looking] to support and promote health and well-being in our community," he says.
"The doors are wide open to local groups to help celebrate and lobby around LGBT issues, and we hope anyone who supports our work – be they local book groups, bars, community associations or business associations – will get involved in the various events in some way."
While the majority of the action in 2012 will be in the capital itself, Birrell is keen to adopt an inclusive approach to people living further out of London. "We want input from any group of supporters, particularly those living anywhere in Greater London, as to the sorts of events they would like to stage and attend."
He adds that people should not feel they have to be LGBT themselves in order to have an input into the itinerary.
While previous Pride events suggest that practically every hotel room in the capital will be booked in advance for WorldPride 2012, Birrell is determined that no visitor should feel ripped off by exorbitant prices.
"In collaboration with Visit London, we'll be offering a special package of accommodation, travel and entry to events, and are hoping it will once again be possible to offer people a really good deal in return for their support."
Says Ainsworth-Wells: "It was London that first discovered and catered for the LGBT travel market some 10 years ago, and other big cities are now in the position of having to catch up with us.
"Our hotel partners are well aware that the pink travel market is worth millions of pounds to the capital, but they also understand that, as with the Olympics, it is vital not to put a quick financial win ahead of long-term visitor loyalty. Any overcharging of rooms at the time of WorldPride 2012 would be very damaging for our long-term LGBT tourism prospects."
If the stage is set for hundreds of thousands of visitors to flock to London for WorldPride 2012, the list of events is still at an embryonic stage, says Newport.
"London will be representing the Pride movement globally, and our aim is to attract literally global figures to help us achieve this. We certainly hope it will be as diverse and inclusive of LGBT life as possible," he says.
"We currently have a blank canvas, and while the creative machine is already churning, we are urging supporters to contact us via the London Pride website with their ideas."
With more than 70 events likely to be staged in and around the capital, he adds that London Pride is now looking for sponsors, media partners and funding for the event.
WorldPride 2012 will be held from 23 June to 8 July 2012. www.pridelondon.org