| Reference Number | TPC/5/7/62/3 |
| Title | Diagram of Patchboard Showing Numbers Lower Theatre - National |
| Level | File |
| Date | 15 March 1974 |
| Description | Evershed Power-Optics Ltd drawing number X12617. Original date 7 February 1974. Two copies. |
| Extent | 2 drawings |
| Series | Evershed Power-Optics Ltd Drawings |