Her main role was the protection of the offshore assets of the United Kingdom, including oil and gas installations and fisheries out to the 200-nautical-mile (370 km; 230 mi) limit.

Her long association with the Falkland Islands resulted in the ship's company being given permission to add her name to the roll of honour written in white rocks on the hillside opposite Stanley in 2007.

[2] The Castle class was designed for fisheries protection and oilfield patrol duties in the United Kingdom's exclusive economic zone (EEZ).

They were a follow-on to the interim Island-class patrol vessel which had been ordered in 1975 when the EEZ was extended to 200 miles, and as a result of initial experience with the Islands, was considerably longer in order to improve seakeeping in heavy seas, with the extra length giving greater speed from the same power as the Islands and allowing a large helicopter deck to be fitted.

[1][a] Dumbarton Castle was laid down at Hall, Russell & Company's Aberdeen shipyard as yard number 986 on 25 April 1980 as the second Castle-class patrol vessel.

[16] On 4 August 2020 BNS Bijoy, was damaged in the 2020 Beirut Port Explosions while part of the United Nations Interim Force in Lebanon.