Royal Navy Type 21 Frigates: A Comprehensive Guide
The Type 21 frigates, also known as the Amazon class, were introduced to the Royal Navy in the 1970s. They were designed as fast, general-purpose escorts that could perform patrol, escort and light combat roles.
Although they were criticised for being lightly armed and structurally fragile, they played an important role in the Falklands War and later served successfully with the Pakistani Navy after leaving British service.
Origins and Design Development
The Navy Did Not Draw These Ships
It was two firms, not one. Vosper Thornycroft and Yarrow between them designed, financed and built the class on a fixed price, with the Ministry of Defence undertaking to buy the ships once they were finished. Five came from Southampton and three from the Clyde. The theory was that commercial yards would be quicker and cheaper than the Admiralty's own constructors, and might produce something other navies would want to buy as well. Early bids put a Type 21 at roughly three and a half million pounds against about five million for a Leander, which is exactly the sort of number that makes a Treasury sit up.
It did not work out that way. The 1970s supplied inflation, the Navy supplied changes to the specification once building had started, and the yards discovered that designing a whole warship is a genuinely different discipline from designing a good hull with a nice bridge. HMS Amazon (F169) came out at 16.8 million pounds.
There is a fifty-year joke buried in the names, incidentally. In the 1920s the Admiralty asked industry for a destroyer gathering up everything the Great War had taught, and Thornycroft and Yarrow each built a private prototype: Amazon and Ambuscade. Between them those two ships set the pattern for essentially every British destroyer down to 1945. Half a century later the same two firms were asked the same sort of question, and each gave the new class the name of its own entry in the old contest.
What They Got, and What They Did Not
What the Royal Navy got was the best-looking and, by common consent, the most comfortable frigate in the fleet. The men who served in them adored them, which is not a thing sailors often say about a warship.
What it did not get was margin, and that single word explains everything that went wrong with the class afterwards. An Admiralty design carries spare weight and spare volume deliberately, because over thirty years a warship accumulates sensors, aerials, weapons, computers and people, all of which have to go somewhere and none of which were in the original drawing. The Type 21s had almost none of that reserve. Every addition therefore came out of stability and strength rather than out of a designed allowance, which is why they cracked, why the strengthening had to be welded on, and why they went early.
At around 3,250 tonnes full load and 384 feet in length, the class was compact but capable of high speeds thanks to their Combined Gas or Gas (COGOG) propulsion, which used Rolls-Royce Olympus and Tyne gas turbines. With a maximum speed of over 32 knots, they were among the fastest frigates of their time.
The ships were armed from new with a 4.5-inch gun, a Sea Cat launcher and anti-submarine torpedo tubes, and carried a Wasp helicopter, replaced from 1978 by the Lynx helicopter. However, their relatively light defensive fit became a weakness during the Falklands War.
The other weakness was aluminium, and there was a warning five years beforehand. Aluminium alloy went into these ships to save weight and cost, part of a wider push in the 1960s and 1970s to avoid what the critics of the day called gold-plating. In November 1977 HMS Amazon (F169) had a serious engine room fire off Singapore, started by a fuel leak, in which the ship's own aluminium ladders melted.
It is worth being precise about the problem, because the popular version is wrong. Aluminium alloy does not burn like paper. What it does is lose its strength at temperatures a steel structure would shrug off, and it expands at a different rate from the steel it is joined to, so a hot fire distorts and cracks the join between them. In a ship that means fire and smoke get through decks and bulkheads that would otherwise have held, and the damage spreads faster than the damage control parties can move. That is what happened in Amazon in 1977 with nobody shooting at her, and it is a recognised factor in what happened to two of her sisters in 1982.
Ships of the Class
A total of eight Type 21 frigates were built:
HMS Alacrity (F174)
Falklands War Service
The Type 21s were in the thick of the Falklands War of 1982, seven of the eight going south.
HMS Antelope was hit by two 1,000lb bombs on 23 May 1982, neither of which exploded, and was destroyed the same evening when one of them went off during an attempt to defuse it. She broke in two and sank on 24 May.
The bare facts of that need unpacking, because they are the whole point of her. Antelope was attacked in San Carlos Water on 23 May 1982 by four A-4B Skyhawks. Two 1,000lb bombs went into her, one killing Steward Mark Stephens on the way in, and neither of them exploded. The pilot who put the second one aboard was killed on his run out, flying into her mainmast.
The reason so many bombs failed is the single most important fact of the air campaign, and it is not luck. To get through the missiles and the guns the Argentine pilots had to attack below masthead height, and a bomb released that low has not had the time of flight it needs for the fuse to arm. Thirteen bombs struck British ships without going off. Had even half of them worked, the arithmetic of the war changes.
What that meant aboard was that ships went on fighting with live ordnance sitting in them, waiting for somebody to come and deal with it. Two Royal Engineers, Staff Sergeant James Prescott and Warrant Officer John Phillips, came aboard Antelope to do exactly that. Three attempts to withdraw the fuse remotely failed. On the fourth, using a small charge, the bomb detonated. Prescott was killed and was awarded a posthumous Conspicuous Gallantry Medal; Phillips lost an arm and received the Distinguished Service Cross. The blast opened the ship from the waterline to the funnel and set both engine rooms alight. Commander Nick Tobin gave the order to abandon ship and was the last man off her. She broke in two and sank the next day, and the photograph of her exploding in the dark is the image most people carry of the entire war.
HMS Ardent was lost in Falkland Sound on 21 May 1982 after repeated Argentine air strikes, covering the San Carlos landings. Twenty-two of her ship's company were killed.
Major roles undersells it considerably, and each of them has an account here. HMS Arrow (F173) was the first British ship hit in the war, by cannon fire on 1 May, and three days later went alongside the burning HMS Sheffield to take her people off. HMS Alacrity (F174) ran the length of Falkland Sound alone at night on 10 May to find out whether it was mined, and was fired at by a submarine on the way back.
HMS Ambuscade (F172) was the electronic warfare picket, stationed deliberately where the missiles would come so that she would be found first. On 25 May she picked up two Super Etendards at thirty miles and their Exocets at twenty-two, and put up chaff. Both missiles broke off from her and went on to hit the Atlantic Conveyor, which is one of the grimmer ironies of the war and not something anybody aboard could have influenced: chaff does not steer a missile, it offers it something more appealing to look at.
HMS Active (F171) and Ambuscade spent the night of 13 to 14 June firing in support of the final attacks, Ambuscade putting 228 rounds into Wireless Ridge for 2 Para. HMS Avenger (F185) sailed late, stayed to the end, and at one point put herself between an anti-ship missile and a carrier and engaged it with her 4.5-inch gun.
HMS Amazon, though not sent south, remained active in Cold War deployments.
She was not idle, either. Amazon spent 1982 on the Armilla Patrol, the standing Royal Navy deployment set up in September 1980, immediately after Iraq invaded Iran, to keep warships alongside British merchant shipping in the Gulf and the Strait of Hormuz. It ran for decades. She was not in the South Atlantic because she was already somewhere else the country had decided it needed a frigate, and she went south later that year, between August and November, once the fighting was over.
There is a certain irony in which ship it was. Amazon had already shown the class what a serious fire could do to it, in 1977, and she was the one that never had to find out in earnest.
The war revealed both the strengths and vulnerabilities of the class. They were fast and manoeuvrable, but their light construction and limited defences left them exposed.
Post-Falklands Service
After the conflict, the surviving six ships continued to serve during the 1980s, though structural cracking became a recurring issue. Strengthening work was carried out, but by the early 1990s the class was withdrawn.
All six surviving ships were sold to the Pakistani Navy, where they were modernised and served into the 21st century.
An Entire Class Emigrated
It is worth stating how unusual that was. Between 1993 and 1995 every single surviving Type 21 was sold to Pakistan in what amounted to a job lot, and they became the Tariq class, named after the first handed over. Amazon became Babur, Ambuscade became Tariq, Arrow became Khaibar, Alacrity became Badr, Avenger became Tippu Sultan and Active became Shah Jahan. A whole class of British frigates changed flag together, minus the two that had been sunk.
Pakistan then made them last. Sea Cat came out and Phalanx went in, Harpoon was added, and Avenger went through a modernisation at Karachi so extensive that she went in a general purpose frigate and came out reclassified as a guided missile destroyer. They worked the Gulf of Aden, the Gulf of Oman and the Arabian Sea, and some of them went into Combined Task Force 150 alongside the navy that had built them.
Most of them ended as targets, which has its own symmetry for ships designed to survive anti-ship missiles. Avenger was expended on 27 April 2020, Active on 12 January 2021 and Arrow in the SEASPARK exercise of 2022. Alacrity was decommissioned in April 2013. Only Ambuscade escaped it: PNS Tariq was decommissioned on 5 August 2023 after thirty years and given by the Government of Pakistan to a British naval heritage group, with the intention of bringing her back to the Clyde where Yarrow built her.
Technical Features
Displacement: 3,250 tonnes full load
Length: 384 feet
Propulsion: COGOG system with Olympus and Tyne gas turbines, 32 knots maximum speed
Armament (as built): 1 × 4.5-inch Mark 8 gun, 1 × quadruple Sea Cat launcher, 2 × triple anti-submarine torpedo tubes, 20mm guns. Four Exocet launchers were added in refits from the mid-1980s, but no Type 21 had them as built and HMS Antelope never carried them at all
Upgrades: Additional 20mm and 30mm cannon added after the Falklands
Aviation: Flight deck and hangar for one helicopter. A Wasp as built, a Lynx from 1978 after trials in HMS Amazon
Crew: Around 177 officers and ratings
Legacy and Replacement
The Type 21 frigates were a bold experiment in privately designed warships. Despite their flaws, they proved valuable in service and demonstrated the Royal Navy’s adaptability during the Falklands.
Their later success in the Pakistani Navy, where they served for decades after their Royal Navy careers ended, highlights the resilience of the design. In British service they were succeeded by the more robust Type 23 Duke class frigates.
The Eight Ships
Built by Vosper Thornycroft at Southampton. HMS Amazon (F169), HMS Antelope (F170), HMS Active (F171), HMS Ardent (F184) and HMS Avenger (F185).
Built by Yarrow at Scotstoun on the Clyde. HMS Ambuscade (F172), HMS Arrow (F173) and HMS Alacrity (F174).
Lost. Ardent, 21 to 22 May 1982 in Falkland Sound, twenty-two of her ship's company killed. Antelope, 23 to 24 May 1982 in San Carlos Water.
Sold to Pakistan. The other six, between 1993 and 1995, as the Tariq class. Four have since been expended as targets or scrapped, one was decommissioned in 2013, and one, the former Ambuscade, is intended to come home.
A Class That Went Early and Left a Long Shadow
The Type 21 frigates may have been controversial, but they earned their place in Royal Navy history through hard service and sacrifice. Fast, adaptable and brave in action, they were a product of their era and proved their worth in the South Atlantic.
Their long second lives in Pakistan underline their lasting value as warships.
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Lee writes the ship histories and fleet features for Hampshire Prints. He served in the Royal Navy, and some of the modern fleet photographs on this site are his own, taken from the Portsmouth shoreline.
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