Supercalifragilisticexpialidocious! Julie Andrews and Dick van Dyke pop in for singsong

Not only does it feature Emma Thompson and Tom Hanks, stars of Saving Mr Banks – about the making of Mary Poppins – but also the original film’s stars Dame Julie Andrews and Dick Van Dyke.

They were reunited after 50 years, and both still looked in fine fettle.

Dame Julie, 78, and Van Dyke, 87, helped to belt out Let’s Go Fly A Kite, one of the hits from Disney’s 1964 hit film, at the US premiere of the Thompson/Hanks movie on Monday.

Also joining the singalong were co-stars Colin Farrell and former West Wing actor Bradley Whitford, screenwriter Kelly Marcel and actress Kathy Baker. Hanks, 57, plays Walt Disney, who spent 20 years trying to persuade author PL Travers (Thompson) to let him put her beloved flying nanny on the silver screen.

Disney, who had promised his daughters he would make the film, found a fierce rival in the formidable Travers, whose long list of stipulations included no animation, no songs – and no Dick Van Dyke.

Emma, 54, was stunning in a champagne-coloured dress with lace trim, joking with Hanks and his actress wife Rita Wilson during the premiere at the Disney studios in Burbank, California.

Meanwhile Van Dyke and Dame Julie looked delighted to be together again to celebrate a new film telling the story behind one of the biggest successes of their careers.

Mary Poppins was the first major screen role for Andrews, following a successful career on stage, and landed her the best actress Oscar.

Emma could be following in the veteran star’s footsteps with Oscar buzz already surrounding her performance in Saving Mr Banks.

The film centres on PL Travers’s life, shifting between her childhood and the terse negotiations with Disney in 1961.

Flashbacks show the writer’s troubled youth in the Australian outback with her alcoholic father – played by Farrell, 37 – a bank worker who may have inspired Travers to create Poppins’s employer, Mr Banks.