Graham Norton was at the party (hopefully he still has enough energy for West End Eurovision tonight!)
As was Miranda Hart, with Miranda co-star Sarah Hadland
Everyone say 'awwww...'
Biggins! With cast member Tamsin Carroll (who plays Ellen)
Lyricist Alain Boublil with 18-year-old Eva Noblezada, who plays Kim
Jonathan Pryce - who played The Engineer originally - with his wife Kate Fahy
Jimmy Carr with his partner Karoline Copping
Principal cast members Alistair Brammer, Eva Noblezada and Jon Jon Briones with Cameron Mackintosh
Check out the full gallery from Dan Wooller below
And watch our exclusive opening night video...