| Company | Timeline | Status | |
| Campbell (Dunmow) Holdings Ltd Director • Unreported | 12 Jul 2021←4 Years→Current | Active | |
| Campbell Associates Limited Director • Unreported | 25 Jan 1999←26 Years→Current | Active | |
| Campbell Associates Limited Secretary • Consulting Engineer | 25 Jan 1999←4 Years→11 Feb 2003 | Active | |
| Institute Of Acoustics Limited (The) Director • Engineer | 17 Apr 1996←9 Years→19 Apr 2005 | Active | |
| Cirrus Research Plc Director • Acoustics Engineer | 1 Feb 1994←1 Year 4 Months→19 Jun 1995 | Active | |
