| Company | Timeline | Status | |
| The William Johnston Family Company Limited Director • Retired | 8 Jul 2022←3 Years→Current | Active | |
J & J Putt Associates Ltd Director • Director | 18 Mar 2010←6 Years→13 Dec 2016 | Dissolved | |
| Johnston Family Trust Limited Director • Computer Systems Designer | 27 Nov 1991←32 Years→12 Apr 2024 | Dissolved | |
