Michael Ball and Alfie Boe have helped to transform what was meant to be a ‘filler’ show into one of the biggest hits in the West End.

The two stars — Ball plays Inspector Javert and Boe, Jean Valjean — lead the staged concert of Les Miserables at the Gielgud Theatre, which will have a live broadcast onto 600 cinema screens for one night only in the UK and Ireland on Monday, December 2, before being beamed later to venues in the United States.

Les Miserables opened 34 years ago as a Cameron Mackintosh production, in association with the Royal Shakespeare Company.

The impresario devised the concert version at the Gielgud when the adjoining house, the newly named Sondheim Theatre, was closing for refurbishment.

Alfie Boe (pictured as Jean Valjean) has helped to transform what was meant to be a ‘filler’ show into one of the biggest hits in the West End

The concert show will be running at the Gielgud until November 30, with the full version of Les Miserables moving back into the Sondheim on December 18.

‘I did it to have a presence for Les Miserables on Shaftesbury Avenue,’ Cameron said of the high-wattage concert that has become a hot ticket event. ‘It was a filler, for a few months.

‘I didn’t think it would have this much life,’ Mackintosh told me yesterday, of this version — and the phenomenon that is Les Mis. ‘No show in history has ever had this life.’

The concert show will be running at the Gielgud until November 30, with the full version of Les Miserables moving back into the Sondheim on December 18. Pictured: Michael Ball as Inspector Javert

Mackintosh went through the family album: the original production, directed by Trevor Nunn and John Caird; the 25th anniversary extravaganza at the O2, where Boe, unforgettably, sang Bring Him Home; Tom Hooper’s Working Title award-winning film; a ‘new’ stage version; and now, the concert model with orchestra, stadium lighting and an ensemble that includes Carrie Hope Fletcher, Matt Lucas, Katy Secombe, Shan Ako, Lily Kerhoas, Bradley Jaden, Rob Houchen and John Owen-Jones.

They will all be featured in the live broadcast. Universal plan to release a DVD and live album early in 2020.

Mackintosh said that late next year, or early 2021, the staged concert will go on tour — both here and abroad. He said the full set (at 60ft wide, it’s not fully opened out at the Gielgud) is easily transportable.

I finally caught up with the Gielgud iteration on Wednesday, and it rocked the house, generating megawatts of electricity. The show, by Claude-Michel Schonberg, Alain Boublil and Herbert Kretzmer, still has the power to move

‘This version can play two or three concerts a week, at 3-5,000 seater stadiums — or go into theatres,’ he said.

‘Michael, Alfie, Carrie and Matt would probably do it again,’ he added.

I finally caught up with the Gielgud iteration on Wednesday, and it rocked the house, generating megawatts of electricity.

The show, by Claude-Michel Schonberg, Alain Boublil and Herbert Kretzmer, still has the power to move.