Six appliances arrived and firefighters wearing breathing apparatus and using heat seeking cameras entered the building to try to find the cause of the smoke.
Unfortunately, after a couple of hours had passed, the seat of the fire could not be established either in the theatre or the adjoining library building.
After much discussion, with the safety of the public the foremost consideration by all concerned, a decision was taken by the Theatre and Fire Brigade that it was not going to be safe to allow the public into the theatre for some time. It was announced to the waiting audience that the show would regrettably have to be cancelled and that any ticket monies would be refunded.
The Hollies were very disappointed that they could not perform tonight and although they were prepared to wait for some time to be able to do so, it was clear as time went on, it was not going to be possible.
The theatre was not declared safe for staff to enter untill approx 20.33 but there was still the smell of burning throughout the theatre. It would not have been pleasant for anyone to have been in there, particularly for any length of time and with the doors shut.
The cause of the incident is being investigated but it is believed to be a mechanical fault in the ventilation system. Unfortunately, it was this very system that was needed to clear the theatre of any smoke and to provide the fresh air which would have allowed for the show to continue.
See here for info from the London Fire Brigade.
See here for photographs.