Notably, he received praise from the Sultan of Brunei for his efforts to bolster the nation's defense forces.

[6] He was appointed an instructor at the Staff College, Camberley, in 1965, commander of the Royal Brunei Armed Forces in 1969 and Director SAS in 1972.

[6] Simpson succeeded Lieutenant Colonel H.F. Burrows as the commander of the Royal Brunei Malay Regiment (AMDB) on 1 May 1969.

The week-long exercise showcased their capability in breaking enemy lines in the jungles and rivers of Brunei.

[10] On 23 September 1970, the wife of Simpson officiated the KDB Masna ship launch ceremony at the Vosper Thornycroft shipyard in Tanjong Rhu, Singapore.