It was a hot July night in 1950, and Guyancourt bar owner Claude Blondeau decided to take a quick stroll around the local airfield before turning in for the night. Suddenly, his peaceful walk was rudely interrupted by a whistling sound "like the wind" as a pair of "perfectly round" flying saucers touched down.

An oval door opened in each craft, and two short men dressed in brown overalls stepped out. They tinkered around replacing "a sort of rod" on the exterior of one of the saucers, working with their bare hands without tools.

Blondeau approached the strangers and asked if they had broken down. "Yes, but it will soon be alright," replied one, speaking very slowly and carefully. Then each went back inside his own craft.

Peering though the open door into the brilliantly lit interior of one of the saucers, Blondeau saw only a red leather "dentist's chair" and an oversized steering wheel equipped with knobs and switches. Fascinated, he asked what the switches were for. "Power!" replied the little pilot curtly, then both machines hurled themselves into the sky "like two shooting stars".

A simple breakdown and repair, perhaps. No more than the alien equivalent of changing a tyre. And it was, perhaps, sheer good luck that Blondeau happened to be in the right place at the right time to see it. But, then again, perhaps not. Because, like a recurring dream, the same scenario has been played out over and over again in every corner of the world.

It happened again in Abbiate Buazzone, Italy, one rainy afternoon in 1950. Bruno Faccini was coaxed outside by the sight of mysterious sparks flying through the air and discovered a group of men in bulky "diving suits" repairing a flying saucer in a nearby field. He thought they must be American test pilots until he approached them to offer assistance and they began to make guttural "gurr gurr" sounds. They shot a brilliant flash of light at him, knocking him flying backwards, then climbed aboard their saucer and took off with a sound like "the amplified buzz of a bee".

A similar scenario occurred in Denmark in June, 1951. While enjoying a country stroll, mechanic Joseph Matiszewski heard a whistling sound and saw a craft descend into a meadow. An eerie silence fell over the pastoral scene as the birds stopped singing and the cows in the meadow stood quiet and motionless as though paralysed.

Matiszewski himself was immobilised when he tried to walk towards the craft, and could only stand and watch as four figures in shiny black suits and translucent helmets emerged to carry out some brief repairs. Then the machine shot skywards, and he was once again free to move.

In 1968, a security guard on his rounds in Milan stumbled across a domed pancake-shaped craft in a courtyard. Two figures in blue overalls and black helmets were busy repairing it. When the guard approached and asked if they needed any help, they leapt into the craft and quickly ascended in a bright flash of light.

The breakdown gambit has even been used as a prelude to abduction. Driving along a country road late at night in Kansas in 1972, an anonymous witness was attracted by a strange bright light in a field. He walked towards it and met a tall humanoid with four arms wearing a tight black jumpsuit and skull cap. The humanoid explained that he was making "minor repairs" to his craft and invited the witness aboard - after which his memory of events became disjointed and dream-like, although he vaguely recalled being shown around a "space station".

Things weren't much different behind the Iron Curtain. Awakened by an irritatingly loud buzzing sound, a citizen of Moscow peered through his bedroom window one night in 1980 to see a small man making repairs to a large dark something-or-other in the street outside. The witness returned to bed, and moments later a brilliant flash illuminated the room. Next morning he woke up with a splitting headache.

Again in Moscow, gas worker Victor Petrovich was busy in his workshop late one night in 1989 when a disc-shaped craft landed on a flat roof nearby and its six-man crew went straight to work on it. Victor summoned some security guards, but they were unable to see the craft or its occupants and left in disgust.

One of the crew - an elderly man who claimed to be from Planet Z - engaged Victor in conversation, lamenting that children on Earth these days behaved terribly. When Victor asked if he could visit Planet Z, he was told that he needed to know more about life on his own world before he ventured into space! Then the stranger suddenly seemed to be speaking in a bizarre incomprehensible tongue, and Victor was overcome by a wave of fear. He rushed to the guards' quarters and dragged them back to the workshop, but by then both craft and crew had vanished.

Another vanishing act was witnessed by Alibek Karachev on March 28, 1990, after his car splutted to a halt as he was driving home to Izberbash in the early hours of the morning. Stepping outside to look under the bonnet, he saw a large cigar-shaped object hovering just above the road ahead. A female with long wavy hair was standing behind a window in the craft while three figures in heavy diving suits were busy repairing it. Karachev felt a sudden urge to look behind him, and when he turned back, the cigar had disappeared.

Of course, we could take these incidents at face value and conclude that our alien visitors fly around in particularly unreliable spacecraft in constant need of repair. But, on the other hand, several common factors in cases of this type suggest that the entire breakdown and repair scenario may simply be a piece of theatre staged for the benefit of the bewildered onlooker.

The ''breakdowns' always seem to occur in isolated areas where they are seen by only a single witness. Usually, they take place in countryside - in fields conveniently situated right next to the road. If they are staged in cities, it is always in a sheltered courtyard or on a deserted street. (In Victor's case, other witnesses did indeed arrive at the scene, but they were unable to see the unearthly maintenance crew.) And, most puzzling of all, there doesn't actually seem to be anything wrong with the craft. No sooner has the witness comprehended the situation than the whatever-it-is goes soaring up into the sky at a fantastic pace, or - as in the Karachev case - simply disappears.

As if the preceding festival of absurdities wasn't enough to cope with, what are we to think when the familiar scenario is played out in miniature in a witness's bedroom?

One hot summer night in 1965, a Seattle woman woke to see a football-sized sphere floating in through her bedroom window. Suddenly paralysed, she could only watch in astonishment as a ramp unfolded from the sphere and six tiny humanoids in tight uniforms marched down it and began to service their craft. Once the job was finished, the little UFO flew back out into the night and her paralysis dissipated.

Lastly, a case from West Yaroslavl Province, Russia, illustrates how the 'breakdown scenario' can even be played out in the absence of a visible craft:

Elderly grandmother Maria Barabashova was alone in her lakeside hut one cold winter evening in 1939 when there came a knock at the door and a short man wearing grey baggy trousers stepped inside. Startled, Maria quickly made the sign of the cross. The man mimicked her action as if to reassure her, but she couldn't help noticing that he had hooved feet. He introduced himself, claiming a long Indian-sounding name that Maria could never remember, then sat down, quickly tucking his hooves away out of sight beneath his chair.

Maria offered him food and drink, but he would accept only a cup of tea - into which he poured a strange powder before drinking. Then he pulled out an small cigar-shaped object and pushed a button on it, remarking "I must not be late back to my craft - it's had some technical problems". He explained that his craft was being repaired as they spoke, and that he would only need to stay a little while.

Maria suddenly grew very sleepy and felt compelled to go to bed. She woke to find that the stranger had gone, leaving behind him a trail of strange footprints in the snow outside.

Presumably, the repairs had been successfully completed and the Devil's flying saucer was now back up and running again. At least for the time being...