It's the end of an era.

Dippy the dinosaur has left the building.

Gifted to King Edward VII in 1905, a 70 foot long cast of a fossilised dinosaur skeleton discovered in America has been on display at London's Natural History Museum for more than a century.

It's become the country's most recognisable museum exhibit - seen by an estimated 90 million people.

Now it's being replaced by the real skeleton of a giant blue whale...Dippy's 292 plaster cast bones setting off instead on a nationwide tour.

On Profile this week, Mark Coles examines how Dippy the replica Diplodocus has become a national treasure.

Producer Smita Patel Researcher Beth Sagar-Fenton.