The first cosmonaut Yuri Gagarin, a carpenter's son with a military bearing and an easy smile, was the ideal candidate for the Soviet authorities to send on the pioneering flight.

Today he is one of the few idols of the Communist era whose popularity has not waned since the fall of the Soviet Union.

Last year he topped a poll of the most iconic national figures of the 20th century, with his popularity highest among those aged 18-24.

Gagarin's peasant origins undoubtedly worked in his favour in the selection process for the first cosmonaut, between him and his closest rival, Gherman Titov, who came from an educated family of teachers.

He was born in 1934 to a couple who worked at a collective farm and had three other children. In 1941, the Nazis occupied their village close to Smolensk in western Russia, and he was unable to go to school until 1943.

After completing seven years of schooling, he trained as a metalworker and was seemingly destined for a career in factories.

"His path was similar to that of millions of his fellow citizens," said Lev Danilkin, the author of a recent biography of the cosmonaut.

In a speech later, Gagarin called himself "a simple Soviet man".

Passionate about aeroplanes from childhood, Gagarin joined a flying club at the age of 20 and later trained as a fighter pilot at a military training school in the town of Orenburg in the Ural mountains.

One day in 1959, the call went out for airforce volunteers to train to fly a "new type of apparatus" and it turned out that Gagarin's small stature, around 1.60 metres (five foot three inches), was an advantage.

The 20 volunteers began year-long secret training in Moscow and the surrounding region. They were later whittled down to 12 and then to six, including Gagarin.

The fair-haired young man with blue eyes and an open smile had the looks of a poster boy, but he also won the liking of his colleagues and especially of Sergei Korolev, the brilliant mastermind of the space programme.

"Gagarin was not a leader, but he was friends with everyone and Korolev treated him as if he were his own son," cosmonaut Boris Volynov, a contemporary of Gagarin, remembered.

In 1961, Gagarin was picked for the first manned mission to space, with the date fixed for April 12.

At 27, he was already married to a nurse called Valentina, who was pregnant with their second daughter.

The mission was perilous for Gagarin. Out of 48 dogs sent into orbit, 20 had died.

Nevertheless "everyone dreamed of being in his place", Volynov told AFP.

"Yuri was chosen for his personal qualities. He was very close to the people."

In a letter written to his wife before the flight and published this year, Gagarin said he believed the spaceship was reliable but added a more emotional note.

"If something happens, you should know everything to the end. I have lived so far honestly, truthfully and to the benefit of the people, even if it was a small one."

He quoted famed Soviet pilot Valery Chkalov as saying that "if you are going to be at all, then be first".

When he returned to Earth and worldwide acclaim, Gagarin carried out his role with grace, witnesses said, recalling his disarming simplicity.

Three months after the flight, he dined with Queen Elizabeth II and was said to have admitted candidly that he did not know which fork to use.

"Gagarin was the most successful propaganda project for the Soviets," said his biographer Danilkin.

Now enjoying the privileges of the Soviet elite, Gagarin shared them with his friends, spending hours on the telephone to get hold of medicine, a hospital bed or a ticket to the Bolshoi for his many friends, Volynov recalled.

That's not to say there were not any incidents, with the cosmonauts the same age as footballers.

In 1961, Gagarin jumped off a balcony, scarring his face, after his wife apparently discovered him in another woman's hotel room, Nikolai Kamanin, who was in charge of cosmonaut training, wrote in published diaries.

Television footage from a few years after his space flight shows he had put on weight and appeared out of condition.

Kamanin wrote in his diaries that Gagarin spent too much time at receptions and that everyone wanted to drink a toast with him.

"Everyone wanted to drink with Gagarin 'for friendship', 'for love' and for a thousand other reasons, and to drink to the bottom of the glass," he wrote in 1968.

His role completed, Gagarin was unable to develop as a cosmonaut or pilot. He was too precious to the Soviet publicity drive to risk any more space missions and he had to beg the authorities to lift his flight ban.

In 1968, Gagarin was allowed to return to flying, initially with a co-pilot.

On March 27, 1968, while flying a small training plane, he crashed north-east of Moscow in an accident whose reasons are still unclear. The file on the investigation remains a state secret.