| Alan Philip Clark | Director | 2 Mar 2020 | 2 Nov 2021 | British | 59 years |
| Edward John Michael Bramson | Director | 31 May 2017 | 15 May 2018 | American | 75 years |
| Karen Martha Forrester | Director | 23 Dec 2014 | 31 Dec 2019 | British | 67 years |
| Murray Hennessy | Director | 21 Jul 2015 | 30 Nov 2018 | Irish | 65 years |
| Owen Henry Wilson | Director | 21 Jul 2015 | 31 May 2017 | British | 50 years |
| Robert Barclay Cook | Director | 9 Dec 2019 | 2 Nov 2021 | British | 60 years |
| Shakira Omowunmi Araba Adigun-boaye | Director | 19 Dec 2014 | 21 Jul 2015 | British | 40 years |
| Stephen Louis Welker | Director | 22 Jun 2017 | 1 Nov 2021 | American | 43 years |
| Stuart Alan Greener | Director | 23 Dec 2014 | 30 Nov 2019 | British | 64 years |
| William De Bretton Priestley | Director | 9 Dec 2014 | 31 May 2017 | British | 58 years |