Arrested decay: Ally Pally theatre

Alexandra Palace's East Court is newly reopened, with an exhibition, coffee bar ... and theatre. 

Through the huge glass atrium is a very special space, reopened for performances after eighty years - but not restored. Instead, it has been put in a state of 'arrested decay' and this fantastic decision means it retains a unique atmosphere. 

The theatre first opened in 1875, but it wasn't the best design - its architect John Johnson had more experience of concert halls, and basically sized one up to accommodate a theatre audience of 3,000. The auditorium may have been unsatisfactory, but the stage machinery was state-of-the-art. By the end of the century, films were also being shown here.

During the First World War, Ally Pally held interned foreign nationals and the theatre became a chapel, although films were also shown. Further work was carried out for its reopening in the 1920s. It enjoyed a golden period under the management of Archie Pitt, husband of Gracie Fields. She trialled many of her productions here before taking the on national tours or West End theatres. By the 1930s, it was out of use and the BBC took it over as a props store. The 1980s fire at Alexandra Palace was the last straw, and the theatre became derelict.

A great deal of care went into keeping the decaying splendour of the theatre intact while also making it a safe, usable space for its users. The lath and plaster ceiling with its decorative mouldings (added in the 1920s) was stabilised, so it won't be falling on the audience's heads - but no more than that was done. Holes and exposed areas have been left unchanged. 

The floorboards were carefully lifted so the crumbling supports could be replaced, then laid back in their original positions. During the work, detritus which had made its way under the floor was retrieved and the best finds - including some fantastic old lightbulbs - are now on display in the East Court. 

Paintwork has also been preserved in its distressed condition. Loose detritus was carefully brushed off, then the panels were sealed with a clear coating.

Retractable modern seating and flexible staging will allow the theatre to be used for all sorts of performances - and have addressed some of the original theatre's flaws, for example by improving sightlines. Forthcoming performances are already proving popular, and it's wonderful to know that this theatre has a new lease of life - without losing any of its older charms.