Cher kept choreographers working late to ensure her dance scenes in 'Mamma Mia! Here We Go Again!' were perfect.

The 'Believe' singer plays Ruby Sheridan in the musical movie - also starring the likes of Amanda Seyfried, Lily James and Dominic Cooper - and she didn't want to leave Shepperton Studios in Surrey, England, until she had mastered the moves.

Speaking exclusively to BANG Showbiz the franchise's associate choreographer, Nichola Treherne, revealed: ''She is charming, she works so hard we would be working with till the hourly hours.

''I remember one evening having to say to her, we've got to finish you are so tired, you can hardly stand up. She was like, 'No, one more time.' I was like, 'No, you've got to stop.' ''

Nichola's colleague Lucy Bardrick added how she was keen to get the routines perfected before anyone else working on the film saw her perform.

She said: ''We were the latest we'd ever been at Shepperton Studios because she is a perfectionist. She wanted us to get it just right with us in the room before anyone else could see it and work on it.''

The 72-year-old icon previously admitted she was ''terrified'' joining the project as a newcomer.

She said: ''I was terrified because everyone had been together and my character wasn't very liked, so I was nervous, but everyone was nice to me. Meryl was behind a piece of scenery watching me do my number and that made me feel good after the fact. It was hard to go on a set where you were a stranger to everyone. I knew some of the people, but to have such a 'mean grandmother' thing and then work your way into the story and be friends with everybody ... but I felt really kind of loved and kind of a great grandmother.''

'Mamma Mia! Here We Go Again' is in cinemas now.