With her sister ship HMNZS Waikato she relieved the Royal Navy frigate HMS Amazon in the Indian Ocean during the Falklands War.

This was due to F 421 being a more modern RNZN frigate, with then current Rn surveillance radar and ESM and a more effectively insulated frigate from nuclear fallout, with the Improved Broad Beam Leander steam plant, for example, being remote controlled and capable of unmanned operation and therefore the ship provided a more effective sealed citadel for operations in areas of nuclear explosions.

However plans for a US Edo sonar and chaff decoys and to arm the Wasp with the Anglo-French AS-12 small anti-ship missiles were not introduced due to cost and for political reasons.

[8] F421 small GP computer was able to assess the radiation level and its up to date electronic warfare sniffers immediately identify a French P-2 Neptune, on 50,52 IFF bands sweeping the area, flying low, with radar, ECM ESM and visual search for the location of unwanted naval, protest yacht and possibly submarine activity.

[12] In November 1974, Canterbury deployed with Destroyer Squadron 5 of the United States Pacific Fleet off the West Coast for six months,[13] the first time a RNZN frigate had operated as an integral part of a U.S. Navy force.

While such joint operation was common for the RAN, it was not repeated in the 20th Century by the RNZN, possibly because while the deployment was approved by the Kirk/Rowling 3rd Labour Government, there was considerable official comment when the frigate returned to Devonport bearing the prominent insignia, US DESRON 5 and because integrated operations were restricted by lack of funding by the following Muldoon government for common Link 10 data link communication systems and baseline HYCOR chaff defence systems,[14] and the standard for RNZN frigates was compatibility rather than commonality with, USN FF52 Frigates[15] In April 1977, Canterbury and the Australian destroyer HMAS Brisbane were assigned to escort the Australian aircraft carrier HMAS Melbourne during a five-month return trip to the United Kingdom for the Queen's Silver Jubilee Naval Review.

[16] Priority for a planned new frigate (either a Type 21 frigate or Dutch Kortanear) and modernisation of HMNZS Taranaki, projects later cancelled by the Muldooon government, meant F421 received only a 12-month refit in 1980 to maximise seatime, and its mid life refit was delayed to Nov 1987 to June 1990, at a cost of $73 million,[17] the most significant changes fitting of Dutch LW08 long range surveillance radar, Phoenix electronic warfare systems and general replacement of radar and sonar with new solid state systems in place of the original obsolescent, British equipment.

After the Argentinian invasion of the Falkland Islands in 1982, New Zealand Prime Minister Robert Muldoon offered to send Canterbury to join the Royal Navy's task force sailing south to retake the British territory [citation needed].

The British MoD refused to fit the US Edo sonars (also planned for an RAN version of the Type 21 frigate rejected by the Australian Government in 1968)[21] and the NZ government - on cost grounds - rejected the new Doppler 184M sonars fitted to HMS Apollo, Achilles and Diomede being built alongside Canterbury in the Yarrow yard[22][self-published source?]

The rather dated solid state sensors fitted were finally replaced as totally obsolescent, in the delayed mid life refit of the Canterbury between Nov 1987 and June 1990 costing $73 million.

The 1991 audit office review of the refit raised some issues, over the cost and need, for new 'long range' air surveillance,[23] LWO8 radar, but lacked the background to assess the relevance of maintaining the Leander frigates, historical role, as a fleet radar picket for operating with the RN fleet or whether the 4.5 guns and Seacat missiles were still useful, given RN reassessment and more accurate reporting, by 1991 of their failure as AA weapons in the Falklands war of 1982.

[24] During the Armilla patrols in 1982–83, the RNZN ships were not able to fully support the RN frigates Arrow and Galatea they were patrolling with in the Indian Ocean, because Prime Minister Muldoon refused to allow them to enter the Persian Gulf due to sensitivities with relations with Bahrain,[25] The Arrow and Galatea were partly equipped for the missile age with computer datalinks and anti-missile decoy systems which fitting to RNZN frigates was delayed.

It was determined that only when a captain commanded a frigate (as the senior officer afloat) would this insignia be displayed – which never occurred again in the Royal New Zealand Navy.

Her duties included escorting landing craft through territory disputed with Indonesia, being the Dili guard ship and patrolling East Timor's waters.

[32] It was expected that the ship would be able to be sunk late 2007, after potential contaminants and scrap materials had been stripped out, and the Department of Conservation had withdrawn its objections at the end of 2006.

[31] After some delays, on 3 November 2007 at 14:30 hrs[citation needed] she was eventually sunk by imported plastic explosives placed at 12 locations around the hull (totalling only 14 kg (31 lb) in weight).

[33] The sinking was prepared by Norman Greenall, once Chief Petty Officer (shipwright) on Canterbury,[34] who has undertaken the scuttling of other New Zealand Navy ships (like HMNZS Wellington).