Design The first decision required was how many Polaris boats should be built. While the
Avro Vulcans to carry Skybolt were already in service, the submarines to carry Polaris were not, and there was no provision in the defence budget for them. Some naval officers feared that their construction would adversely impact the
hunter-killer submarine programme. The number of missiles required was the same as the number of Skybolt missiles, which were considered sufficient to devastate forty cities. To achieve this capability, the BNDSG calculated that this would require eight Polaris submarines, each with 16 missiles with one-megaton warheads. It was subsequently decided to halve the number of missiles, and therefore submarines, based on a decision that the ability to destroy twenty Soviet cities would have nearly as great a deterrent effect as the ability to destroy forty. The Admiralty considered the possibility of hybrid submarines that could operate as hunter-killers while carrying eight Polaris missiles, but McNamara noted that this would be inefficient, as twice as many submarines would need to be on station to maintain the deterrent, and cautioned that the effect of tinkering with the US Navy's 16-missile layout was unpredictable.
The Treasury costed a four-boat Polaris fleet at £314 million by 1972–1973. A
Cabinet Defence Committee meeting on 23 January 1963 approved the plan for four boats, with the Minister of Defence,
Peter Thorneycroft noting that four boats would be cheaper and faster to build than eight. A mission led by Sir
Solly Zuckerman, the
Chief Scientific Adviser to the Ministry of Defence, left for the United States to discuss Polaris on 8 January 1963. It included the
Vice Chief of the Naval Staff, Vice Admiral Sir
Varyl Begg; the Deputy Secretary of the Admiralty, James Mackay; Rear Admiral
Hugh Mackenzie; physicist Sir
Robert Cockburn; and F. J. Doggett from the Ministry of Aviation. Its principal finding was that the Americans had developed a new version of the Polaris missile, the A-3. With a range of , it had a new weapons bay housing three re-entry vehicles (REBs or Re-Entry Bodies in US Navy parlance) and a new
W58 warhead expected to become available around 1970. A decision was urgently required on whether to purchase the old A-2 missile or the new A-3, as the A-2 production lines would shut down within two years. The Zuckerman mission came out strongly in favour of the latter, although it was still under development and not expected to enter service until August 1964, as the deterrent would remain credible for much longer. The decision was endorsed by the
First Lord of the Admiralty,
Lord Carrington, in May 1963, and was officially made by Thorneycroft on 10 June 1963. While the Zuckerman mission was in Washington, R. J. Daniel of the
Royal Corps of Naval Constructors led a deep technical mission to the United States to study the latest developments in the design of ballistic missile submarines. They met with Rear Admiral
Pete Galantin, Raborn's successor as the head of SPO, and executives at the
Electric Boat Company, which was building the American Polaris boats. While it was desirable to hew closely to the American design, this would involve retooling the British shipyards and purchasing American equipment. An alternative proposal was to take the incomplete nuclear-powered
hunter-killer submarine , cut it in half, and insert the Polaris missile compartment in its midsection. This was a path that the Americans had taken with the in order to build ships as quickly as possible in order to address the
missile gap, the purported numerical superiority of the Soviet Union's missile force, which turned out to be illusory. Daniel was opposed to this on the grounds that it would unduly disrupt the hunter-killer submarine programme, and it would add more new features to a design that already had enough. The chosen design was suggested by Daniel's superior, Sidney Palmer. The reactor section would be similar to that of
Valiant, which would be joined with a machinery space to the American-designed but mainly British-built missile compartment. The forward section would be of a new design. The boat would have a
displacement of , more than twice that of , the Royal Navy's first nuclear-powered submarine. Following British practice, the boats would be identical, with no deviation allowed. The value of this was driven home by a visit to the
submarine tender , where the costs of non-standard components were evident.
Organisation The project was formally named the
British Naval Ballistic Missile System. The Board of the Admiralty met on 24 December 1962 and decided to adopt Le Fanu's proposal that a special organisation be created to manage the project. It did not create a replica of SPO, however, but a smaller administrative and organisational
cadre. Mackenzie, the
Flag Officer Submarines (FOSM), was informed on 26 December 1962 that he would be appointed the Chief Polaris Executive (CPE); the term was henceforth used to refer to both the man and his organisation. Rowland Baker, who had been the head of the Dreadnought Project Team, was appointed the Technical Director.
Captain C. W. H. Shepard, who had worked on the
Seaslug missile project, became the Deputy Director for Weapons, and Captain Leslie Bomford was appointed the Polaris Logistics Officer. The creation of this position was the only significant departure from Le Fanu's original blueprint. Some staff were assigned to the Polaris Executive and responsible only to the CPE; but there were also "allocated staff", who were seconded to the Polaris Executive, but who remained responsible to another organisation, such as the Directors-General of Ships and Weapons; and "designated staff", who were not employed on the Polaris project full-time, and remained part of their parent organisations. Mackenzie established his own office and that of his immediate staff in London, which he considered was necessary in order to be in immediate contact with the Admiralty, the ministers, and the key departments. He was initially given two rooms and a closet at the Admiralty. Most of the Polaris Executive was located in
Bath, Somerset, where the Admiralty's technical and logistics departments had been relocated in 1938, "the connection between bath, water and boats having not escaped the administrative minds in Whitehall." Initially they were accommodated in the Admiralty complex there, spread over three different sites. To allow the Polaris Executive to be co-located, a block of single-storey prefabricated offices was built at Foxhill on the south side of Bath, which was occupied in February 1964. By 1966, including allocated but not designated staff, the Polaris Executive had 38 staff at the London office, 430 in Bath, 5 at the
Ministry of Aviation, and 31 in Washington. An early issue that arose concerned the relationship between the Polaris programme and the hunter-killer programme. At this time point,
Valiant was under construction, but the second boat of the class, , was yet to be
laid down at Barrow. The possibility of the two projects competing for resources was foreseen, but the Admiralty elected to continue with its construction. The interdependence between the two projects extended well beyond the shipyard;
Valiant would be the first boat powered by the
Rolls-Royce pressurised water reactor, which would also be used in the new Polaris ballistic missile submarines. In early 1963 the reactor was still in the prototype stage at
Dounreay. The overlap between the two projects was sufficiently substantial that in May 1963 it was decided that CPE would be responsible for both. The Joint Steering Task Group (JSTG) was established by Article II of the Polaris Sales Agreement. It was modelled after the Steering Task Group that oversaw the Special Projects Office. It met for the first time in Washington on 26 June 1963. The respective liaison officers acted as the secretaries of the JSTG. These were appointed in April 1963, with Captain
Peter La Niece taking up the position in Washington, and Captain Phil Rollings in London. The agenda for the meetings was normally agreed about three weeks beforehand via an exchange of
teletype messages, with position papers exchanged about a week beforehand. Meetings were normally held over three days. Initially the JSTG met quarterly, but this was reduced to three times a year in 1965. The flow of information tended to be towards the UK. The JSTG was not an adversarial forum, but from the start there were disagreements over the scope of the Polaris Sales Agreement, which the staff of CPE saw as open-ended, but that of SPO saw as limited in nature.
Construction The choice of
Vickers-Armstrongs as
shipbuilder was a foregone conclusion, as its yard at
Barrow-in-Furness in
Cumbria was the only one in the UK with experience in nuclear-powered submarine construction. The firm was thoroughly familiar with the heightened requirements nuclear-powered submarine construction entailed in terms of cleanliness, safety and quality control, and the government had already spent £1.5 million upgrading the yard's facilities. The only concern was whether the large Polaris boats could navigate the shallow
Walney Channel. A formal
letter of intent was sent to Vickers on 18 February, and its selection as lead yard was publicly announced on 11 March 1963. The question then naturally arose as to whether Vickers should build all the Polaris boats. Given the size of the yard and its labour force, and the desired speed of construction, the Admiralty decided that Vickers would build two boats, and the others would be built elsewhere. Tenders were invited from two firms with experience in building conventional submarines,
Cammell Laird in
Birkenhead, and
Scotts in
Greenock, on 25 March. Cammell Laird was chosen, and a letter of intent was sent on 7 May 1963. Some £1.6 million of new equipment was required to prepare the yard for Polaris work. Two berths and the jetty were rebuilt, and works were also necessary on the roads and river wall. A
cofferdam was built to allow construction of a new
slipway and other works to be carried out in dry rather than tidal conditions. New facilities were also added in Barrow, and the Walney Channel was dredged. Traditional
battleship or
battlecruiser names were chosen for the Polaris boats, signifying that they were the
capital ships of their time. All were named after ships that Mountbatten had served on. The first boat, , was laid down by Vickers on 26 February 1964; the second, , by Cammell Laird on 26 June 1964. They were followed by two more boats the following year, one at each yard: at Barrow on 16 June 1965, and at Birkenhead on 19 May 1965. The Polaris boats became known as the .
Resolution was launched on 15 September 1965, and
commissioned on 2 October 1967.
Resolution conducted a test firing at the American
Eastern Range on 15 February 1968. The first Cammell Laird boat,
Renown followed, and was launched on 25 February 1967. The second Vickers boat,
Repulse, was launched on 11 November 1967. Concerns about the Walney Channel proved justified; when the launch was delayed by half an hour due to a protest by the
Campaign for Nuclear Disarmament, the falling tide left insufficient clearance, and the boat became stuck in the mud. Its development involved an increase of about 500 staff at Aldermaston compared to that anticipated for Skybolt, with 4,500 staff expected to be working on nuclear weapons by 1969. When it came to the Re-Entry System (RES), the US Navy was using the Mark 2 Mod 0 RES, but had a new version, the Mark 2 Mod 1 under development. In order to meet Polaris in-service deadline of May 1968, the components had to be ordered by May 1964. The Ministry of Aviation and the Admiralty therefore opted for the Mark 2 Mod 0 RES. To validate the design, a programme of
nuclear tests was required, which was estimated to cost around £5.9 million. This was authorised by Douglas-Home on 28 November 1963. A
series of underground tests were carried out at the
Nevada Test Site in the United States, starting with Whetstone/Cormorant on 17 July 1964. The next test, Whetstone/Courser on 25 September 1964 failed due to a fault in the American
neutron initiators, and had to be repeated as Flintlock/Charcoal on 10 September 1965. This tested a design of the ET.317 using less plutonium. With four Polaris boats each carrying 16 missiles each with three warheads, there were 192 warheads in total. This modification therefore saved 166 kg of plutonium worth £2.5 million. Additional active materials required were obtained from the US. Some 5.37 tonnes of UK-produced plutonium was exchanged for 6.7 kg of
tritium and 7.5 tonnes of highly enriched uranium between 1960 and 1979. Warhead manufacture commenced in December 1966. ==Operations==