Ljs: Royal wedding: Media prepares for enormous TV audience

Estimated 8,500 journalists in London for event, including some big names from major US networks

Hundreds of broadcasters from around the globe will be in specially-designed camera boxes, or crammed into expensively rented office space and balconies overlooking the flag-lined route, while others will take their places in the crowd.

But it is only when you get to Buckingham Palace, where banks of temporary TV studios have been set up next to Canada Gate, that the scale of the media operation for the royal wedding becomes truly clear. It is predicted it may command the biggest audience in TV history.

More than 36 studios, for broadcasters including the BBC, Sky News, ABC, NBC, CBS and al-Jazeera, are housed in the three-storey structure, with outside broadcast vans and other equipment taking up so much space that part of Green Park has been closed to the public.

Two cherry pickers have been set up facing the palace and another broadcast box has been set up by the 82ft Queen Victoria Memorial, for a prime view of the royal balcony kiss.

Inside Westminster Abbey, seated beside the 1,900 guests, will be 40 broadcast cameras, 12 still photographers and 28 reporters from national, international and regional media.

There are an estimated 8,500 journalists in London for the marriage of Prince William and Catherine Middleton, 6,500 of whom are officially accredited by the palace. There are more than 100 overseas broadcasting organisations, most of them from the US.

The BBC, whose round-the-clock coverage will anchored by Huw Edwards at Canada Gate, will have the biggest broadcast presence with around 550 staff at a cost of �2m. Ed Stourton will be the only journalist broadcasting live from within Westminster Abbey, providing commentary for BBC Radios 4 and 5 Live.

Ratings figures for the wedding will not be available until Sunday. But the National Grid is predicting that around 400,000 kettles will be boiled in households across the country after the couple have exchanged vows.

The US networks have sent some of their biggest names to anchor the event, including Katie Couric of CBS, Diane Sawyer of ABC and Brian Williams of NBC.

US broadcasters have also invited a host of British pundits and celebrities to provide the accents and knowledge, including Piers Morgan, Martin Bashir, David Starkey, Patrick Jephson, former equerry to Diana, Princess of Wales, and Colleen Harris, Prince Charles's former private secretary.

Chris Hampson, international news director of NBC News, said: "This is the biggest and the most advanced technical broadcast we've ever done. It is comparable to the US election coverage."

There were two reasons for the huge investment, Hampson said. "First of all we're a very varied organisation, we have a Hispanic channel, we have Access Hollywood, we have E for Entertainment, so we need more people here to provide coverage across the board. Secondly, there's a very big appetite for a royal story, probably a bigger interest than in the UK."

Carolina Valladares, the presenter for Colombian cable channel NTN24, which goes out from Canada to Argentina, said: "In Colombia they cannot understand how a democratic county can still have a monarchy. They are fascinated by this. In Colombia and Venezuela they love celebrities. In Argentina ? well in Argentina, they think it's all a bit stupid."

NTN24 will go out at 4am in Colombia. "We expect people to be awake, but will broadcast again at 2 o'clock."

By the time Prince William leaves Clarence House, British viewers will have had two hours of Royal Wedding broadcasting. But at least they'll be awake.

Following special requests from a string of US networks, Buckingham Palace is to stay lit up until 12.30am, an hour and a half later than usual, so that the palace facade will be illuminated as millions of Americans sit down for prime-time evening bulletins presented live from London.

The US Networks begin their coverage at 5am on the east coast or 3am on the west, hoping for a share of up to 2 billion people estimated to be watching, a figure which dwarfs the 750 million who watched Charles and Diana's wedding in 1981.

British historian Robert Lacey, who will be in prime position in front of the abbey, said he had been working for ABC for at least six weeks. "Until last week, Americans were crazier than we were. They've asked me to do a lot of the historical stuff about the abbey, poets' corner, how the transepts work.

"A lot of us are providing thoughts and information that is news to others around the world.

"In the royal field I honesty think that the only journalist who has ever had any genuinely inside information is Andrew Morton with Diana. I just hope the rest of us are talking common sense."

? This article was amended on Thursday 28 April. We originally quoted Chris Hampson of NBC News as saying: "This is the biggest and the most advanced technical broadcast we've ever done, including the Olympics." This was incorrect. We also quoted Hampson as saying the coverage was "bigger" than US election coverage. This has now been changed.