In 1976 the British astronomer Patrick Moore announced on BBC Radio 2 that at 9:47 AM a once-in-a-lifetime astronomical event was going to occur that listeners could experience in their very own homes. The planet Pluto would pass behind Jupiter, temporarily causing a gravitational alignment that would counteract and lessen the Earth's own gravity. Moore told his listeners that if they jumped in the air at the exact moment that this planetary alignment occurred, they would experience a strange floating sensation. When 9:47 AM arrived, BBC2 began to receive hundreds of phone calls from listeners claiming to have felt the sensation. One woman even reported that she and her eleven friends had risen from their chairs and floated around the room.

I can see some noted HZers with zero critical thinking skills and a strong imagination reporting just that.

The Top 100
Aprils Fools Jokes of All Time.

Another classic for the ever gullible Brits...

On March 31, 1989 thousands of motorists driving on the highway outside London looked up in the air to see a glowing flying saucer descending on their city. Many of them pulled to the side of the road to watch the bizarre craft float through the air. The saucer finally landed in a field on the outskirts of London where local residents immediately called the police to warn them of an alien invasion. Soon the police arrived on the scene, and one brave officer approached the craft with his truncheon extended before him. When a door in the craft popped open, and a small, silver-suited figure emerged, the policeman ran in the opposite direction. The saucer turned out to be a hot-air balloon that had been specially built to look like a UFO by Richard Branson, the 36-year-old chairman of Virgin Records. The stunt combined his passion for ballooning with his love of pranks. His plan was to land the craft in London's Hyde Park on April 1. Unfortunately, the wind blew him off course, and he was forced to land a day early in the wrong location.

and one more time for them Brit folk...

In 1998 Guinness issued a press release announcing that it had reached an agreement with the Old Royal Observatory in Greenwich, England to be the official beer sponsor of the Observatory's millennium celebration. According to this agreement, Greenwich Mean Time would be renamed Guinness Mean Time until the end of 1999. In addition, where the Observatory traditionally counted seconds in "pips," it would now count them in "pint drips." The Financial Times, not realizing that the release was a joke, declared that Guinness was setting a "brash tone for the millennium." When the Financial Times learned that it had fallen for a joke, it printed a curt retraction, stating that the news it had disclosed "was apparently intended as part of an April 1 spoof."