Anthony G Williams

First posted May 2004, last revised March 2014

During the 1970s the major surface warships of the RN underwent several substantial changes in equipment. Steam plant (or a steam/gas turbine combination) was replaced by all-gas turbine machinery in new designs. The Sea Dart and Sea Wolf SAMs were introduced to replace Sea Slug and Sea Cat, and Exocet anti-ship and Ikara anti-submarine missiles acquired. The old semi-automatic 4.5 inch Mk VI twin mounting was replaced by the new automatic Mk 8 in the same calibre. The Limbo anti-submarine mortar was replaced by homing torpedoes. And three new classes of escort ships were developed Type 42 destroyers, Type 22 anti-submarine frigates and Type 21 general purpose frigates plus the Invincible class light aircraft carriers.

The purpose of this article is a 'what if?' think piece, looking at what alternative decisions might have been made at this crucial time, and their possible outcomes, within similar overall levels of resources. Trying to compare costs is made even more difficult than usual by the rapid inflation which occurred over the period of the construction of the new ships and adaptation of existing ones. Accordingly, 1973 has been taken as a baseline (the year when the first of the adapted Leander class was commissioned) and the costs of all of the other ships has been calculated in 1973 prices, using the overall annual inflation figures.

It must be emphasised that this is not intended to be critical of the decisions made at the time; they were influenced by countless political, financial and practical considerations and I have no reason to doubt that those responsible made the best decisions they could, in the light of the information then available.

The RN in 1970

At the beginning of the 1970s, the major vessels in the RN's surface fleet were as follows (displacements given are standard):

Aircraft Carriers

Ark Royal (43,000 tons; steam): just converted to operate Phantoms and Buccaneers

Eagle (45,000 tons; steam): decommissioned in 1972

Hermes (24,000 tons; steam): converted to Commando Carrier 1971-73

Bulwark (22,000 tons; steam)


Tiger (10,000 tons; steam): converted to a Command Helicopter Carrier 1968-72, one twin 6 inch + one twin 3 inch + Sea Cat

Blake (10,000 tons; steam): converted to a Command Helicopter Carrier 1965-69, armament as above


County Class guided missile destroyers (6,200 tons; steam and gas): AA ships, Seaslug + two twin 4.5 inch Mk VI + Sea Cat, 8 commissioned 1962-70

Daring Class gun destroyers (2,800 tons; steam): three twin 4.5 inch, 8 ships commissioned in the 1950s, in the process of being disposed of;

some remaining WW2 ships, most converted to anti-submarine frigates


Whitby/Rothesay/Leander Classes (2,150-2,790 tons; steam): steady evolution of the basic Type 12 design AS frigates, with Limbo + helo (later) + one twin 4.5 inch Mk VI + Sea Cat (later); 41 ships completed 1956-73

Tribal Class (2,300 tons; steam and gas): Type 81 GP frigates, two WW2-era 4.5 inch single mountings + Sea Cat + light helo, 7 ships completed 1961-64

Leopard/Salisbury Classes (2,170-2,300 tons; diesel): related Type 41 AA (two twin 4.5 inch Mk VI) and Type 61 air direction (one twin 4.5 inch); 8 completed 1957-60

Blackwood Class (1,180 tons; steam): economy Type 14 class AS ships with Limbo, 12 completed 1956-58, about to be disposed of

The RN in 1980

By 1980, the following new classes of ships, or significantly adapted ones, were in service or under construction:

Aircraft Carriers

Invincible Class (20,000 tons; gas turbines): Sea Dart, CIWS (later), 3 completed 1980-85


HMS Bristol: single ship of Type 82 Class (6,700 tons steam and gas): fleet escort, Sea Dart + Ikara + 4.5 inch Mk 8, completed 1972 (c.26 million)

Type 42 Class (3,850-4,750 tons; gas turbines): AA ships, Sea Dart + 4.5 inch Mk 8 + Phalanx added to some later, 14 built (2 as replacement for Falklands War losses), completed 1973-1985 to replace County Class. Average cost per ship c. 24m in 1973 prices.


Type 21 (Amazon Class 2,750 tons; gas turbines: GP frigates, 4.5 inch Mk 8 + Exocet + Sea Cat, 8 ships, completed 1974-78 (2 sunk in Falklands 1982). Average cost per ship c. 12m in 1973 prices.

Type 22 (Broadsword Class 4,000-4,200 tons; gas turbines): AS frigates, Sea Wolf + Exocet; 14 completed 1979-90, final 4 with Harpoon + 4.5 inch Mk 8 + Goalkeeper. Average cost per ship c. 34m in 1973 prices.

Modified Frigates

Leander Class Ikara conversions: 8 ships modified 1972-78, losing 4.5 inch mounting in favour of Ikara AS missile system. Average conversion cost per ship c. 8m in 1973 prices.

Leander Class Exocet conversions: 8 ships modified 1975-82, losing 4.5 inch mounting in favour of 4 Exocet ASu missiles. Average conversion cost per ship c. 11m in 1973 prices.

Leander Class Seawolf conversions: 5 ships converted 1980-84, losing 4.5 inch mounting in favour of one Seawolf AA mounting and 4 Exocet ASu. Average conversion cost per ship c. 20m in 1973 prices.

Other 1970 ships remaining in 1980

The two big carriers had gone, and Bulwark went in 1981, leaving only Hermes and Invincible available in 1982

The two Tiger Class Command Helicopter Carriers had also gone by 1980

The Bristol and five of the County Class were still in service

The rest of the Leander Class (about six ships) were still in service.

Elements of the Ships: Engines

In deciding what ships might have been designed to enter service by 1980, an important element is the machinery. All three new classes of escorts used the same COGOG (Combined Gas Or Gas) plant, which consisted of two propeller shafts, each with one R-R Tyne (4,000-5,000 shp) and one R-R Olympus (25-28,000 shp) gas turbine. The two types of engines could not be used together. These engines were marinised versions of aircraft turboprop and turbojet engines respectively. The ships therefore had 8,000-10,000 shp for cruising, with 50-58,000 shp for burst speed. The Invincible Class had a different COGAG (Combined Gas And Gas) arrangement consisting of two propeller shafts each with two R-R Olympus which could be used singly or together, giving a total power of 112,000 shp.

The COGAG arrangement was also employed in contemporary USN escorts, using two 20-25,000 shp gas turbines per shaft. Two propeller shafts (80,000 shp) were enough for the 6,000 ton Spruance Class destroyers, while one (40,000 shp) sufficed for the 2,700 ton Oliver Hazard Perry Class frigates.

One of the Type 22s (Brave) was fitted with R-R Spey instead of Olympus gas turbines, and these were subsequently fitted to the Duke Class frigates of the 1990s. The Spey is less powerful than the Olympus (around 19,000 shp) but more efficient. It was available for aircraft use in the 1960s, and a marinised version would probably have developed around 15,000 shp at that time.

Proposal: to marinise the Spey in the 1970s rather than the Tyne and Olympus, and to use it in a COGAG arrangement, providing 30,000 shp per shaft, rising to 38,000 with development. This would have had the following advantages:

Significantly lower cost to marinise, build and maintain one engine rather than two

Enough cruising power to enable a small escort to manage with only one shaft (15,000-19,000 shp available rather than 4-5,000 shp from one Tyne)

Invincibles could use three or four shafts, cheaper than developing a new gearbox and installation

The disadvantage would have been a higher fuel consumption in low-speed cruising for the two-shaft installations (30,000 shp available, whereas 10,000 was adequate).

Elements of the Ships: Weapons

The Sea Dart was an advanced SAM when introduced, with the advantage over the similar-sized USN SM missiles of an efficient ramjet engine which put its range in the same class as the bigger Extended Range missiles. It utilised a trainable twin launcher (as did SM at the time). The USN later adopted a VLS (Vertical Launch System) for its SMs, as that was simpler and more reliable and the VLS silos could be easily used to launch other missiles of similar size.

The RN purchased the French Exocet anti-ship missile, which was launched from substantial fixed boxes.

The RN also purchased the Australian Ikara anti-submarine missile, which was like a small radio-controlled aeroplane carrying a homing torpedo. It was launched using rocket boosters, and then glided to its target. The installation required a 'zareba'; a circular mounting to launch it from.

Proposal: to develop a VLS system for Sea Dart from the start. This would also be used to house Exocet missiles, and an Ikara-type missile; ideally, the Australians would be persuaded to develop Ikara to fit. The advantages would be:

Much less expensive and space-consuming than the three separate launcher installations

More reliable than a trainable launcher (the Sea Dart launcher had some reliability problems in the Falklands)

More versatile in allowing a VLS-equipped ship to vary its armament to meet requirements

More export opportunities for Sea Dart, possibly including France and Australia. An increased customer base would have made it more feasible to keep upgrading the missile system.

Sea Wolf was (and remains) a very effective short-range AA and anti-missile system. It was introduced in a trainable six-round launcher, now replaced by a VLS. Ironically, early in its development in the 1960s it was tested with a VLS and it is unclear why this was not proceeded with then. The missile system was also the subject of a very protracted development which greatly increased its cost and delayed its entry into service.

Proposal: develop Sea Wolf as a VLS system from the start, and concentrate on getting the initial version into service quickly, leaving performance improvements to later software upgrades. Advantages:

More flexible in terms of launcher location

More reliable launching, without the need to manually reload

More ships available with Sea Wolf more quickly

Potentially more attractive for export sales, which would also have helped fund upgrades.

The VLS Sea Dart would have required a command guidance system in order to guide the missile towards the target so that its seeker could then pick up the signal and take over. This could be achieved by using the Sea Wolf command guidance system, making the directors dual-purpose. Initially the Sea Dart would use semi-active radar for the rest of its flight, but active terminal guidance could be developed later.

The 4.5 inch Mk 8 gun was (and remains) a satisfactory but unremarkable shore bombardment and secondary anti-ship MCG (Medium Calibre Gun). However, the opportunity could have been taken to strike deals with other countries over 'weapon swaps'; e.g. by acquiring the Italian 5 inch OTO Melara gun, or the French 100 mm, or the Swedish 120 mm Bofors, in return for Sea Wolf and/or Sea Dart systems.

Proposal: that suitable foreign guns be acquired by exchange instead of developing the 4.5 inch Mk 8. Advantages:

                    Cost of developing 4.5 inch Mk 8 avoided

                    Opportunities to extend export sales for other systems

The RN continued to rely for light automatic cannon on the basically WW2 era 20mm Oerlikon and 40mm Bofors, until after the Falklands when there was a rapid switch to modern Oerlikon weapons: the 20 mm KAA in a single mounting, and the 30 mm KCB in single or twin stabilised mountings.

Proposal: to adopt the 30 mm KCB in a single stabilised mounting for the new ships. Advantages:

Much more effective in the AA role, provided laser rangefinder/computer predictor sights were used.

Proposed Ship Classes

To summarise, the RN acquired 15 new destroyers (c. 368 million - all costs at 1973 prices), 14 new anti-submarine frigates (c.470 million) and 8 less expensive new general-purpose frigates (c.100 million) of three different designs from the 1970s onwards, a total of 37 new escort ships. In addition, 21 Leander class ships were extensively modified, with entirely new weapon systems, at a total cost of 245 million (all in 1973 prices). It seems rather odd to spend such a large sum on modifying the Leanders from gun ships by giving them modern weapon systems, while at the same time buying unsophisticated new gun ships in the form of the Type 21 class. In this alternative world, the Leanders would be retained unmodified for a while as gun ships, then be phased out as new frigates with modern weapon systems were introduced.

Several problems with these decisions emerged, largely because the nature of the expected threat changed. In the 1970s the RN was thinking almost exclusively about the threat to North Atlantic trade posed by Soviet surface ships, submarines and long-range missile-carrying aircraft. The ships procured therefore tended to be specialised for particular functions (anti-air, anti-ship or anti-submarine) except for the less capable general-purpose Type 21 frigates, which were bought more or less off-the-shelf.

The 1982 Falklands War drove home the lesson that all ships need to have general-purpose capabilities, even if they are biased towards one major function. So the last batch of the gunless (apart from 40 mm Bofors) Type 22 frigates was modified to carry a 4.5 inch gun, as was the design of the succeeding Type 23 Duke Class ships.

Bearing this in mind, it might have been better to consider a high/low mix of escorts, with some having the full range of functions, and other being smaller and less expensive but still with good all-round capabilities.

Proposal: that two different classes of escorts be developed instead of three, as follows:

Destroyer two-shaft, c.5,500 tons, with c.60 VLS for Sea Dart/Exocet/Ikara, also VLS Sea Wolf, MCG, 30 mm, and a flight deck and hangar for one Sea King or two Sea Lynx helos.

Frigate one-shaft, c.2,750 tons, with c.24 VLS for Exocet/Ikara only, also VLS Sea Wolf, MCG, 30 mm, and a flight deck and hangar for a Sea Lynx.

The key question is: could these have been afforded?

In ship terms (steel and machinery), the destroyer would probably cost about the same as a Type 22 or 42 (the larger ship being balanced by the less expensive machinery), but the weapon fit would be considerably more expensive as it would essentially consist of both types of ship combined. Despite the fact that the Type 22 and 42 were similar in size and had the same machinery, the Type 22 cost an average (in 1973 prices) of 34m compared with 24m for the Type 42. Even allowing for the possible cost savings in weapon procurement indicated, at a rough guesstimate each destroyer would probably cost in the region of 44m.

The frigate would basically be significantly cheaper than the similar-sized Type 21 because of the one-shaft machinery, but again the weapons fit would be considerably more expensive. It is very difficult to estimate the likely cost, perhaps a little more than the Type 42 Batch One, which averaged 17m (later batches were a lot more costly): say 20m per ship for the frigate. In compensation, the Exocet/Ikara/Sea Wolf modifications to the Leander class would have been unnecessary, resulting in a 245m saving.

There is another important element in the savings, and that is the crew. The RN went through a manning crisis in the late 1970s, and the more rapid replacement of the steam Leanders by gas-turbine ships would have led to crew savings.

The total cost of the historic new and modified escorts discussed here (Types 21, 22, 42, 82 and modified Leanders) was in the region of 1.2 billion in 1973 prices. This money applied to the proposed two-class ships would buy 12 destroyers (528 million) and 24 frigates (480 million) for a total cost of just over 1 billion: a significant saving, which could be applied to developing the weapon systems.

Overall, it seems reasonable to project a target of 12 destroyers and 24 frigates to be constructed over the 1970s and 1980s for a similar cost to the actual procurements.

It should be noted that the versatility of the frigates in particular would have made them far more attractive on the export market than the specialised ships actually acquired. A stretched version of the frigate, to accommodate a  radar and crew needed for Sea Dart, could also have been very attractive to navies looking for an economical escort with some air defence capability. It could have been a serious rival to the American Oliver Hazard Perry Class.

The Invincible Class carriers were bedevilled with political compromises in their development (being originally known as 'Through-Deck Cruisers' in an attempt to fool the Labour government, which was opposed to aircraft carriers). This led to them being planned with the unnecessary armament of Sea Dart and Exocet (although the latter was not fitted). They would certainly have been far better served by a Sea Wolf installation instead, with the emphasis given to increasing their hangar capacity.

Implications: the Falklands War

Assuming that the new ships could have been built at a rate of one destroyer and two frigates per year over a period of 12 years, with the first ones commissioning in 1975, then 7 destroyers and 14 frigates would have been in service, fully worked-up, at the time of the 1982 Falklands War. Every one of them would have had Sea Wolf, backed up by 30 mm guns, which would have made them vastly more effective in the savage battles with Argentinian aircraft around San Carlos Water. Each one would also have had an MCG for shore bombardment. Equipping Invincible with Sea Wolf would have reduced the risk to the carrier, possibly enabling her to operate closer to the battle zone to the benefit of Sea Harrier availability. Of course, a great benefit would also have resulted from the earlier introduction of the Sea King Searchwater AEW helos, developed in a rush just too late for the Falklands.