When John Wilkins, Bishop of Chester, a founder of the Royal Society and one of the few men to have been master of a college at both the universities of Oxford and Cambridge, wrote the first tale about a spaceship in 1640, it could hardly have been said to be an instant success. A Discourse Concerning a New Planet (the follow-up to his 1638 work The Discovery of a World in the Moone) discusses a voyage to the Moon, but it was ridiculed left, right and centre.

Margaret Cavendish, Duchess of Newcastle, herself a natural philosopher and early science fiction writer, is reputed to have said that the idea would never catch on because there were no pubs along the way. She meant that long-distance journeys in the 17th century were very much dependent upon inns and taverns en route to provide shelter, sustenance and a change of horses for weary travellers.

Adverse opinions didn't stop Wilkins and his student, Robert Hooke - destined to be famous in his own right as a philosopher, architect and inventor - experimenting with an idea for using gunpowder to launch space vehicles 20 miles into the air, waiting for the Earth to turn and then bring them back to terra firma thousands of miles away. These were primitive satellites. Nor did they stop the great Sir Isaac Newton from refining their idea by pointing out in Principia Mathematica (1687) that, because of gravity, a cannonball fired with sufficient velocity from a mountain top would go into orbit.

Two hundred and seventy years later with the advent of multi-stage rockets, Sputnik 1 gave a demonstration of these basic theories of spaceflight. Four years after Sputnik, on 12 April 1961 - 50 years ago this week - a cramped five-tonne space capsule called Vostok 1 ("East") carried Yuri Gagarin on a complete circumnavigation of the Earth in 90 minutes, with about 20 minutes to get up and down. In becoming the first cosmonaut, Gagarin easily beat the science fiction writer Jules Verne, who imagined it would take 80 days to go around the world, although he anticipated doing so in a hot-air balloon.

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The Duchess of Newcastle has been proved very wrong. Just over 500 humans from nearly 40 countries, making more than 1,000 trips, have followed in Gagarin's footsteps. She was definitely mistaken with respect to tourists - seven have paid their own way and Virgin Galactic, the commercial company set up to fly researchers into space, has several hundred potential customers signed up for suborbital flights. As yet, only 24 Apollo astronauts - of whom only one, Harrison Hagan "Jack" Schmitt, was a scientist - have become interplanetary explorers by venturing as far as the Moon. One can only hope that the European Space Agency's Human Spaceflight and Exploration division realises its ambitions to go back soon.

Funnily enough, when I was recruited to the Apollo programme, it was only because someone who was expected to take the job turned it down ("It doesn't have any long-term career prospects," he said). I hope he doesn't kick his cat every time I'm on the telly. While I have obviously proved him wrong, it disappoints me that only one of the 500 space travellers, Helen Sharman, was a fully paid-up Brit because successive UK governments have been human spaceflight-averse. Others with British connections, such as Michael Foale and Piers Sellers, qualified for Nasa flights through dual citizenship or naturalisation.

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Only 10 per cent of the astronauts and cosmonauts have been women, although the first creature in space, Laika, a dog, was most definitely female (because it was easier to arrange her toilet facilities). Making the trip is not without risks, as the doomed canine discovered. When the British press learned from a Russian scientist that Laika's flying kennel had "no brakes", animal lovers protested outside the Soviet Embassy (there were no such protests after Gagarin's voyage).

Since that time, 17 spacefarers have lost their lives leaving or returning to Earth. Gagarin himself was killed, aged 34, piloting a jet fighter; he would have just celebrated his 77th birthday had he survived.

Gagarin was a poor boy who made good. Born the son of a carpenter on a collective farm, his home village, Klushino, was unfortunately in the path of the invading German Wehrmacht. He, his younger brother and his parents fought tooth and nail to survive, but his two older siblings were seized as slave labourers (they too survived). When the Second World War ended, he attended a technical school then became an apprentice metalworker and a part-time student.

While at college he managed to wangle some flying lessons, which made him determined to join the Soviet Air Force; very soon he had ascended the ranks to become a test pilot. Then he was approached for a top-secret project that required hot-shot flyers. In a short time he found himself in a group of 20, being centrifuged and shut up for hours in a blacked-out, soundless room. The Soviets were preparing to put a man in space.

Gagarin proved unbreakable as the 20 became six and were finally whittled down to two. On 9 April 1961, with just three days' warning, he was told he would be "The One".

So Gagarin beat the US' first man into space, Alan Shepard, hands down - or perhaps that should be trousers down, for on the way to the launch pad, Gagarin stopped the bus and urinated against one of its wheels. This became a cosmonaut tradition.

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Shepard wasn't so lucky. He was beaten into space by a month (he only went straight up and down without orbiting) and, after sitting on top of a Redstone rocket for a launch that was delayed for hours, he couldn't wait any longer. He announced to mission control, "Man, I got to pee", and urinated in his suit. Clearly, better toilet arrangements had been made for space dogs.

Speaking of dogs again, in a final rehearsal less than three weeks before the real thing, the Soviets flew a duplicate Vostok capsule, number 3KA-2, carrying a wooden dummy and a dog, Zvezdochka, or "Little Star". After a single orbit, the dummy was ejected on re-entry and landed by parachute, while Zvezdochka remained inside. She survived the landing, which meant that Gagarin had two alternatives for how he ended his mission. He chose the parachute and was reportedly greeted by a cow and a couple of peasants, from whom he asked directions to a phone so that he could report to Moscow. As man's first spaceflight was at the height of the Cold War, the use of the parachute was not revealed at first in case it led to Gagarin being disqualified for not completing the journey by landing in his ship.

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Gagarin's surrogate dummy, nicknamed Ivan Ivanovich, can be seen at the Smithsonian National Air and Space Museum in Washington. Vostok 3KA-2 was due to be auctioned at Sotheby's in New York this week on the anniversary of Gagarin's flight. The guide price was $2 million-$10 million (?1.2 million- ?6.1 million).

Gagarin's flight took place just after 9am Moscow time. It was still the middle of the night at Nasa's launch centre in Florida. When journalists heard the news, one decided to ring Nasa for a quote. On getting through to the press officer, John "Shorty" Powers, he was greeted by an angry voice: "What is this? We're all asleep down here." Predictably, one headline the next day read: "Soviets Put Man In Space. Spokesman Says US Asleep".

Having completed man's fastest lap of the planet, Gagarin set off on a rather slower world tour. In July 1961, he visited the UK, met Prime Minister Harold Macmillan and had lunch with the Queen at Buckingham Palace. The Royal Society also treated him to lunch - a signed menu exists to commemorate the occasion.

The British Interplanetary Society gave the pioneer spaceman a gold medal, which he was able to put with a similar honour bestowed by the Amalgamated Union of Foundry Workers. To get the latter he had to travel to Manchester. It was raining, but as a man of the people, the "First Cosmonaut" insisted on travelling to Trafford Park in an open car.

Back in London, he made a propaganda visit to Karl Marx's tomb in Highgate Cemetery. My colleague John Zarnecki, professor of space sciences at The Open University, was given the day off school to stand and cheer in the crowd.

John is one of the contributors to a website, , which tracks Gagarin's British trip with lots of donated photographs, reminiscences of events and archive film footage. An 108-minute film, which reproduces the entire space odyssey showing the view from Vostok 1's flight path, is downloadable from to celebrate one of the most remarkable journeys in history.

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