| Company | Timeline | Status | |
| Callum Automotive Ltd Director • Director | 1 May 2024←1 Year 5 Months→Current | Active | |
| Callum Creative Ltd Director • Engineer | 17 Jul 2020←5 Years→Current | Active | |
| Ian Callum Design Ltd Director • Engineer | 24 Nov 2018←3 Years→6 Jan 2022 | Dissolved | |
Muirhead Engineering Limited Director • Engineer | 25 Nov 2013←3 Years→18 Apr 2017 | Dissolved | |
