How could we

played by Streep – is still alive in the sequel. Fears surged when she was left out of the first trailer, and her on-screen pals referred to her only in the past tense.

The follow-up trailer did little to ease fans’ worries, as Streep was barely present and had no lines. Bosses are taking a chance on eager early filmgoers keeping the secret under wraps.

Lily James – who plays young Donna in flashbacks alongside newcomer Josh Dylan as young Bill – told an interviewer: “The story is so brilliant and people are going to love it so much that I don’t want to spoil anything.”

In the sequel Donna’s daughter Sophie, played by Seyfried, returns home pregnant and single.

Her mum’s pals Rosie and Tanya tell her in flashbacks how Donna handled the same situation, uncertain if the baby’s father was Sam, Harry or Bill.

Julie Walters, who returns as Rosie, admits she had her doubts about a sequel.

The 68-year-old comedy legend revealed: “I couldn’t see how it could work and what they could do with us. My first reaction was, ‘Oh God no, it’s going to be awful’. But the script was so good. I think it’s fantastic. It’s better than the first one.”

The new instalment is expected to smash the 2008 worldwide box office take of €526million – for a film that cost €32million to make. The original was the year’s top movie in 15 countries and has been seen by 60 million people.

While Seyfried, 32, plays Donna’s daughter Sophie in the reboot, Streep’s mum is played by a newcomer to the saga, Cher.

The music icon – seen in trailers singing ABBA hit Fernando – told how she did not

My first reaction was, ‘Oh God no, it’ll be awful’ JULIE WALTERS ON HER FEARS OVER FILM SEQUEL