It's an occasion that might make even Mr Grumpy crack a smile. The colourful Mr Men children's books are celebrating their 50th birthday.
The popular series has now entered its sixth decade in 2021, surviving its British creator Roger Hargreaves thanks to the dedication of his son.
"It is an amazing fact that we've reached half a century, it's a very long time for a series to be so successful," Adam Hargreaves said.
The books' enduring popularity after the first story's publication in 1971 is an indication of "how strong my father's idea really is", he added.
The younger Hargreaves played no small role in the genesis of the Mr Men and the Little Miss series that followed, whose characters are named after the emotion or behaviour they embody.
It was his own childish question - "one of those impossible questions that children like to pose to their parents," he said - that prompted his father to draw the first Mr Men character.
"My question was: 'what does a tickle look like?'" Mr Hargreaves explained.
In response, his father drew a little orange man with a blue hat and arms of incredible length. Mr Tickle was born.
The character became a book, and that book, in turn, became a runaway success, even leading to a television series.
Over the following years, Mr Tickle was joined by a cohort of friends, including the perpetually smiling Mr Happy and the accident-prone, heavily bandaged Mr Bump.
The Little Miss series followed 10 years later.
Since their inception, some 250 million copies of the small square books have been sold in 30 countries around the world, from Britain to China, and translated into 17 languages.
Mr Hargreaves said that his father had always been ambitious about the books and saw the potential of the series.
"But in terms of whether he thought it would have lasted for 50 years I don't think he could have imagined that, half a century on," he said.
