On April 1st 1993 Westdeutsche Rundfunk, a German radio station, announced that officials in Cologne had just passed an unusual new city regulation.

Joggers going through the park would be required to pace themselves to go no faster than 6mph.

Any faster, it was felt, would unnecessarily disturb the squirrels who were in the middle of their mating season.

Hoax proves a royal washout

Late in March 1860 numerous people throughout London received the following invitation: “Tower of London - Admit Bearer and Friend to view annual ceremony of Washing the White Lions on Sunday, April 1st 1860. Admittance only at White Gate. It is particularly requested that no gratuities be given to wardens or attendants.”

By twelve o’clock on April 1st a large crowd had reportedly gathered outside the tower. But of course, lions hadn’t been kept in the tower for centuries, particularly not white lions.

Therefore the crowd eventually sneaked away disappointed.

This prank had a very long pedigree. It had often been perpetrated (on a smaller scale) on unsuspecting out-of-towners, and an instance of it is recorded from as far back as 1698.