Inside the Rehearsal Room with Gary Barlow's musical The Girls

There can be few stage properties that have begun as a film, adapted into a play and further adapted into an original piece of musical theatre. Gary Barlow and Tim Firth's new musical The Girls does just this, bringing the now familiar story of a fearless group of W.I ladies who began raising money for Leukaemia Research by creating their own naked calendar back to the stage in a heartfelt and refreshing new British musical. Following almost five years of development, the musical lands in London's West End following successful runs in the Lowry in Salford and the Grand Theatre in Leeds.

Barlow and Firth grew up in the same village in the North of England and have been friends for the past 25 years. The Girls marks their determination to write a musical together, shepherded into existence by producer David Pugh and an incredibly talented cast of performers.

This week we attended an exclusive rehearsal for the production, performed in front of the creative team including Mr Barlow himself, alongside some of the musical's harshest critics - the original 'Calendar Girls' themselves from the Rylstone Women's Institute.

Speaking at the rehearsal event, producer David Pugh told about the development process for the musical which has had 112 songs written for it and is also around twenty-six percent different to the production that premiered in Leeds and Salford. Following multiple workshops in London the show had its regional premiere in its original form at the Burnsall Village Hall in front of an audience of VIPs, invited guests and the original ladies themselves. From there, the creative team worked solidly to tell this remarkable story in an honest yet ultimatley fresh way that would translate to a piece of modern musical theatre.

The tragedy that inspired the original calendar, the death of John Baker, remains important to not only the show's central message but the production team and cast as a whole. At the rehearsal event, John's daughter Rachael watched alongside the girls themselves, giving a standing ovation to the performers who brought a number of key moments from the story to life. Pugh was proud to announce that the show and cast have helped raise money for Bloodwise throughout each of the musical's runs, raising £75,000 during the five weeks of performances in Leeds and Salford. The achievement, however wonderful, is overshadowed by the hugely impressive figure that the calendar girls themselves have raised which is currently edging towards an incredible £5million, and ever rising.

The West End cast for The Girls includes an incredibly talented company of musical theatre performers, all of whom performed at the rehearsal event. West End regulars Joanna Riding, Claire Moore, Sophie-Louise Dann and Michele Dotrice led the full company in the opening number "Yorkshire" which colourfully introduces each of the characters and sets the tone for Barlow's lively and highly emotive musical score. After a spirited opening, the assembled audience was treated to a couple of more intimate moments, firstly from Olivier Award-winner Joanna Riding who plays Annie, opposite James Gaddas as her husband John, whose death inspires the extraordinary bravery of the group.

The hilarious Claire Moore performed an inspiring number as Chris, the florist who first comes up with the idea of the group making their own risqué calendar, knocking a powerful number right out of the park. Finally the cast presented a group number staged at the W.I Convention staged in solidarity for their cause as each of the women come forward to pledge their commitment to the project, a memorable moment from the film that becomes equally exciting on stage.

It was clear from watching just in the rehearsal room how powerful each of these numbers has the potential to be, with the story pulling on the heartstrings as well as providing some extremely funny moments of light relief. The show feels distinctly British in style and tone, with Firth's adaptation expanding on the familiar characters whilst allowing memorable moments from both the film and stage play to reappear. Barlow's score embraces his popular musical background yet inherits musical theatre traditions that help tell the story and allow audiences to connect to the material in a wholly original way. Memorable melodies, witty lyrics and a set of fantastic performances come together to make this an exciting new musical to grace the West End.

The Girls begins performances at the Phoenix Theatre on 28 January 2017. The Girls tickets are now on sale.