By Maria Golovnina
LONDON, July 11 (Reuters) - At noon London time on July 12, 2012, Britain will slip silently into a new era of radio history.
At the top of the hour, the BBC World Service - once the voice of the British empire - will transmit its last radio news bulletin from its imposing home, Bush House in central London.
For more than 70 years the art-deco building was the beating heart of the British Broadcasting Corporation's overseas service and a bastion of press freedom around the world.
From here King George V addressed the Empire in 1932, Charles de Gaulle defied the Nazis, and legions of emigres sent news in dozens of languages to the unmistakeable introductory strains of Lilliburlero, its signature tune.
Setting off a wave of nostalgia, the BBC has decided to move the operation to a gleaming new office in London as part of its efforts to bring all of its broadcasting teams under one roof.
With a warren of meandering corridors, soaring halls and marble stairs, the majestic Bush House has already been mostly abandoned, with the last team of journalists due to leave officially on Thursday after the final bulletin.
"It's spooky. It does feel bereft," said Andrew Whitehead, a former South Asia correspondent who has worked for the BBC since 1981, his footsteps echoing in the building's hollow silence.
"Part of me feels sad. Bush House has meant something. You would say: 'I work at Bush House'. You don't say: 'I work at the BBC World Service'."
Marking the birth of Britain's broadcasting tradition, the BBC's Empire Service, as it was known at the time, was launched in 1932, helped by new radio technology that allowed it to send signals over vast distances.
Its boss at the time was not very optimistic, quipping once that its programmes would "neither be very interesting nor very good". Yet it expanded fast, soon beaming news in dozens of languages into some of the world's most far flung corners.
From its grand location off the Strand in central London, Bush House witnessed every turn of history throughout the drama of the 20th century, its culture shaped by the gripping years that followed World War Two.
It has been described as an organism in itself with a United Nations like atmosphere where journalists from all over the world rubbed shoulders in its polyglot canteen.
"I certainly remember that very strong physical impression and the smell of the place from the very first time I went there," said Peter Horrocks, the BBC's Director of Global News.
"It's a building that inspires huge affection and emotion especially for the staff who have come from around the world, many of whom are exiles and people who can't go back to their countries of origin. It provides something of a refuge."
This is the building from which General Charles de Gaulle sent daily support messages to the Free French movement after France fell to Nazi Germany in 1940.
It is also the place whose labyrinthine corridors and newsrooms are said to have inspired British author George Orwell to form his vision of the Ministry of Truth in his novel "1984" describing a totalitarian future society.
At the height of the Cold War, trouble sometimes struck too close to home. In 1978, BBC Bulgarian Service journalist Georgi Markov died in mysterious circumstances after being jabbed in the leg by an umbrella tip containing highly toxic ricin near London's Waterloo Bridge.
Banned by the secret police from having a telephone, the Czech dissident Vaclav Havel once used to sneak into a local post office to record secret interviews with Bush House studios.
"Bush House in the Cold War years (was once) described as a place with various Eastern Europeans and Russians walking down the corridors smoking rank cigarettes and muttering to each other conspiratorially," Maya Samolov from the former BBC Yugoslav Service told a BBC programme.
"But there wasn't really that much to spy on because we were in the business of broadcasting," Samolov added with a laugh.
Millions of listeners around the world, from Nigeria to Pakistan, feel they know the place personally after countless programmes introduced with the words "From Bush House in London".
For both friends and foes, Bush House was a powerful symbol.
At the height of the Cold War, Russian spies were specifically instructed to listen to its bulletins - with anti-Soviet bits meticulously cut out - as part of their training, according to Oleg Gordievsky, a double agent in the KGB.
"The World Service has very particular values attached to it, which were born out of the war years," said Robert Seatter, Head of BBC History. "It's all the world there in one place."
In some repressive regimes, listening to Western news reports could land people in jail.
Dissidents from the Eastern bloc still like to recall how they used to huddle in secrecy around their radios in tobacco smoke-filled flats in Prague or Moscow, thirsty for snippets of news from the outside world.
For many of them, the BBC's "This is London" - a phrase preceding news bulletins at the top of the hour - rang out like the echo of a world they thought they would never see.
Myanmar's opposition leader Aung San Suu Kyi, who paid tribute to BBC staff during her visit to London last month, said a music request programme on the World Service called "A Jolly Good Show" gave her comfort during her years under house arrest.
"Because of the BBC I never lost touch with my people, with the movement for democracy in Burma and with the rest of the world," Suu Kyi said during her visit.
Described by the BBC as a quintessentially British building, Bush House was originally commissioned as a symbol of Anglo-American trade - hence the inscription on its facade reading "Dedicated to the friendship of English speaking peoples".
When it opened in 1925, Bush House was considered the most expensive building the world, its cost estimated at two million pounds. When the BBC's lease expires at the end of this year, it will return to its Japanese owner.
The BBC says the move to a new office building is necessary because it wants to encourage efficiency and creativity through new and better broadcasting technology.
"It's an old building now. It's not fit for purpose," said Horrocks. "People want to carry their memories and the spirit of Bush House with them into a new environment and modern technology."
At the end of the day, listeners may not notice any difference. But for many it is still an emotional moment.
Its former inhabitants have been seen streaming back to the building recently for a last stroll through its empty corridors, to say goodbye to their memories and an epoch fast slipping way.
Whitehead smiled sadly as he recalled his years as a young reporter in the 1980s when he used to sift through wads of colour-coded news agency copy as part of his job.
"Reuters was green, AP was white, AFP was pink," he said. "Your hands got absolutely bloody filthy because of the carbon."
He added: "Journalists tend to be fairly cynical and hard-bitten. They like to see themselves as not very nostalgic. But leaving this building, God, it's been..." Whitehead paused. Lost in his memories for a moment, he did not finish the phrase. (Writing By Maria Golovnina; Editing by Giles Elgood)