Wear and tear over the years had taken their toll on the grid, with heavy steel-framed sets and moving lights causing major operational challenges for the theatre staff.

Owners the Ambassador Theatre Group commissioned Theatreplan to prepare a detailed report on the existing flying system and suggest a new support arrangement to accommodate modern scenery loads. The task was complicated because of the presence of six large early wooden drum and shaft mechanisms. These had been listed and English Heritage and Westminster City Council wanted them retained.

Theatreplan produced a comprehensive 'heritage' report, an exercise which resulted in Listed Building Consent to move four sets of drums and shafts to an off-stage location and to dispose of the remaining two sets.

The grid was not only restricted by its design and loading limitations. A cross-over bridge positioned between the fly floors downstage prevented any flying within this important section of the grid immediately upstage of the proscenium. Consent was given to remove the bridge and replace it with a new bridge at the rear of the stage. A new main steel joist was installed to alleviate the grid load on the proscenium wall, which had suffered some damage over the years.

During the same six-week window in late 2011 that Theatreplan was working on the grid and flying system replacement, the owners took the opportunity to commission Foster Wilson Architects to renovate the auditorium with new lighting positions and restoration of damaged plasterwork.

Further work, addressing a sighting problem experienced by flymen when observing the stage floor during scene changes, saw Theatreplan - working in conjunction with the theatre's structural engineers - specifying an unusual back-loaded counterweight system. This is mounted on the onstage edge of the original fly gallery and accessible from both sides ? off-stage to load and on-stage to operate ? the new position also taking full advantage of the height of the stage right mansard roof.

Twenty double purchase counterweight sets have been installed at the venue, recently renamed the Harold Pinter Theatre, each with a payload of 350kg, plus two 350kg capacity fixed-speed electric hoists. Provision was made to install chain hoists from new grid steel beams. The grid was also re-slatted with new timber and remains in use for light loads suspended on hemp sets.

Image © Mathew LLoyd