| Company | Timeline | Status | |
| Queen Anne Street Practice Limited Director • Director | 3 Sep 2012←10 Years→17 Jul 2023 | Active | |
| The Analytic Practice (No. 1) Limited Director • Director | 3 Sep 2012←10 Years→17 Jul 2023 | Active | |
| The Group Analytic Practice Limited Director • Director | 31 Aug 2012←10 Years→17 Jul 2023 | Active | |
| Ian Williamson Limited Director • Psychotherapist | 21 Aug 1996←29 Years→30 Sep 2025 | Dissolved | |
