| Company | Timeline | Status | |
| John Holt Architects Limited Secretary • Unreported | 1 Aug 2007←18 Years→Current | Active | |
| John Holt Architects Limited Director • Architect | 1 Aug 2007←18 Years→Current | Active | |
| William J Holt Architects Limited Director • Architect | 28 Mar 2003←20 Years→5 Sep 2023 | Dissolved | |
