Adults who, for whatever reason – a dose of nostalgia, they have had children of their own or don’t want to watch food shows on a Saturday morning – drift back to watching cartoons they saw in their youth, will often be comforted by the fact that, although decades might have passed and some attempt at updating beloved characters has often occurred, the heroes largely remain the same.

Scooby-Doo’s pals in Mystery Inc are eternal teenagers, Rupert the Bear is still refreshingly youthful (even with a CGI makeover) and the Mr Men remain ageless coloured blobs. But there is a growing trend for modern cartoon characters to do what their animated ancestors never did – grow up.

The latest children’s character to do a Tracy Barlow and walk down the stairs several years older and with a new look is Dora the Explorer. Since her introduction in 1999, this cute little Mexican girl and her talking monkey boots have educated and charmed children across the world, at the same time as emptying their parents’ pockets thanks to a merchandising campaign carried out with military precision and ruthlessness.

Now toy-maker Mattel, working with Dora’s TV company Nickelodeon, has come up with a new ‘tween’ Dora. Gone are the pudgy little girl legs and pudding-bowl haircut, to be replaced with a trendy leggings-and-tunic combination and flowing auburn locks.

After concerns from parents, Mattel said that the new Dora – aged about ten – wasn’t replacing the cartoon Dora beloved of pre-schoolers, but was a marketing device confined to dolls and other merchandise.

But a cartoon where the character has made the leap to the verge of adulthood is Ben 10. Anyone with primary school-aged children will be painfully aware of ten-year-old Ben Tennyson, who owns a hi-tech watch which enables him to change into myriad space aliens – initially it was ten, but when little boys want action figures, what can you do but add more alien DNA to that darned watch?

Last year saw a new version of Ben 10 on the screens – Alien Force fast-forwarded five years to bigger versions of Ben, cousin Gwen and enemy-turned-ally Kevin. These smarter 15-year-olds do the same stuff but are now the same age as those kids who grew up with the original cartoon.

Where will it all end? If modern cartoon characters get a makeover every five years or so, perhaps when my children are the same age as me they’ll be tuning into the adventures of a more subdued Ben Tennyson, knocking 40 and wondering where it all went wrong, while rising air fares have put the brakes on Dora’s exploring and she’s regretting giving up a life full of prospects to marry some guy with a dead-end job.

To which we say, hopefully not.