Depending on the precise date, there were plenty of Wessex in Borneo 1965 onwards.
The RN operated 845 and 848 turn and turn about, orginally with the single engined Mk 1 and later the twin engined Mk 5.
To refer back to an earlier post the RAF had three guys with 845 (Harry, John and Al) so in a sense the RAF had Wessex in Borneo by proxy.
BomberH, the RAF and RN worked remarkably well together during Confrontation, particularly when the RN needed a Belvedere to lift a Wessex out of some remote place (except the occasion when the unslung Wessex started to swing and the Belvedere pilot stamped on the hook quick release, sending the Wessex to its unmarked final resting place somewhere under the trees).