Meryl Streep used to fear that every film would be her last.

The 67-year-old actress' biggest concern when she hit was that she wouldn't be cast in any more movies, but she is proud she still boasts a successful career 27 years later.

Speaking to the Wall Street Journal magazine about her fears for the future, Meryl - who won the Oscar for Best Actress in 2011 for 'The Iron Lady' - said: ''And if you're lucky you can keep working. But everybody has troughs and dismal times - every single person.

''I remember as I was hovering around 40, I thought each movie would be my last, really. And all the evidence of other 40-year-old women at that time - this is 27 years ago - would lead you to believe it was over.''

And the mother of four - who has daughters Mamie, 32, Grace, 30, Louisa, 25, and 36-year-old son Henry with her husband Don Gummer - has admitted she would have been ''unhappy'' if her acting career had of come to an end because of her age.

She explained: ''On a certain level you don't have any choice - you're unhappy if you're not doing it, so you're compelled in a certain way.''

Meanwhile, Meryl is set to join the cast of 'Mary Poppins Returns' and play the role of Mary's cousin, Topsy, who didn't appear in the 1964 classic, whilst Emily Blunt, 33, - who starred with Meryl in the hit film 'Devil Wears Prada' will take on the leading role of Mary Poppins, the character made famous by Julie Andrews.

The sequel is set to be released in December 2018 and will focus on some of the material featured in P.L. Travers' seven additional novels.