Desert Island Discs host Roy Plomley, left, is seen in 1979 with one of his guests on the longrunning radio show: former British prime minister Margaret Thatcher. (Chris Ware/Keystone Features/Getty Images)

Margaret Thatcher chose Beethoven, Michael Caine picked Frank Sinatra and boxer George Foreman selected The Beatles' All You Need is Love.

They are among almost 3,000 guests who have appeared on the radio program Desert Island Discs, a British broadcasting institution that turned 70 on Sunday.

The show's simple format hasn't changed since 1942: Ask an illustrious or famous figure to choose the eight pieces of music they would take with them to a deserted isle, and talk about what the tracks mean to them. At the end of each program, the guest is sent into imaginary exile, along with their choice of a book, a luxury and one of their eight records.

Almost 3 million listeners tune in each week to the show, which has stranded royalty, prime ministers and movie stars, as well as scientists, poets and philosophers. Its success is a mark of radio's enduring popularity in the age of the Internet and high definition TV. Host Kirsty Young said its strength lies in the "unique blend of a castaway's life and the music that forms its soundtrack."

"At best it displays the frailties and strengths of the human condition — how our creativity, grit and humanity can see us through," she said in a BBC radio documentary marking the anniversary.

Young told the Radio Times magazine that scientists made the best guests, because they often had not been interviewed before.

Politics on the air

"Politicians are awful, especially when they have the responsibility of office, because they have to be careful," said Young, one of only four hosts the show has had in 70 years.

Still, politicians rarely refuse an invitation to soften their image. Former prime minister Tony Blair revealed a love of Spanish guitar music, his successor Gordon Brown enthused about Bach and current leader David Cameron selected Bob Dylan's Tangled Up in Blue as his desert island record.

'To be welcomed into something so quintessentially British as Desert Island Discs means I've made it, I'm welcome, I'm home'

—Paul Gambaccini

Even a senior member of the British royal family has appeared. Princess Margaret, sister of Queen Elizabeth II, was a guest in 1981. Her musical choices included Rule Britannia and — more surprisingly — Sixteen Tons By Tennessee Ernie Ford. The probing of the castaways is gentle — a style pioneered by the show's creator and original host Roy Plomley, who plied guests with food and drink at his club before recordings. But the interviews are often revealing and can occasionally make headlines.

There were hundreds of complaints when Lady Diana Mosley, widow of Britain's World War II Fascist leader Oswald Mosley, was a guest in 1989 and offered the view that Hitler "was of course extraordinarily fascinating and clever."

In February 2003, a month before the invasion of Iraq, actor George Clooney accused then U.S. President George W. Bush of manipulating the country into supporting war and said it was Americans' "patriotic duty to question the actions of your government."

Prestigious spot

Few refuse an invitation, which brings no fee but considerable prestige.

"You're honoured to be part of this strange national club," said U.S.-born music broadcaster Paul Gambaccini, a castaway in 2002.

"To be welcomed into something so quintessentially British as Desert Island Discs means I've made it, I'm welcome, I'm home," he told the BBC.

Mick Jagger is one of the best-known holdouts. His Rolling Stones bandmate Charlie Watts said yes, as did ex-Beatle Paul McCartney — who chose his murdered bandmate John Lennon's Beautiful Boy as his desert-island track — and musicians from Bing Crosby to Alice Cooper.

The most popular musical choice over the decades has been the Ode to Joy from Beethoven's 9th Symphony, with Mozart the most frequently selected composer. The most popular non-classical piece is Edith Piaf singing Je Ne Regrette Rien. The most commonly requested luxury item is a piano. Other choices have been more original.

American novelist Norman Mailer requested "a stick of the very best marijuana," while egocentric entertainment svengali Simon Cowell asked for a mirror — "because I'd miss me."