HMS Agamemnon Puts to Sea: Thirteen Years to First Voyage, and Still No Working Attack Flotilla

By Mark Allatt, UK Defence First

This week HMS Agamemnon left Barrow-in-Furness for the first time and headed north for the Clyde. The sixth Astute-class attack submarine passed under the raised Michaelson Road Bridge more than thirteen years after her keel was laid and a year and two days after the King commissioned her. It is a genuine milestone. It is also a portrait of a programme that still cannot turn steel into deployable undersea power at the pace Britain now claims to need.

Agamemnon’s departure ends an extraordinary stretch in which no operational Royal Navy attack submarine was known to be at sea. HMS Anson, the only Astute to have sailed recently, arrived back in Devonport on 27 May after a curtailed Indo-Pacific deployment. One hundred and twenty days followed with the hunter-killer force entirely alongside. Agamemnon is not yet the answer. She faces twelve to fifteen months of sea trials, weapons testing and crew training before she can join the operational fleet. On the pattern set by Anson, that points to late 2027. A boat leaving the builder’s yard is not a boat on patrol.

A programme measured in decades

The Astute class was ordered in 1997 as the successor to Trafalgar. The first keel was laid on 31 January 2001. HMS Astute commissioned on 27 August 2010, nine years later than first planned and after a crisis so severe that, in 2002, work was briefly suspended because the builder no longer knew how to complete the design. Barrow’s workforce had collapsed after the Cold War, from some 13,000 people to around 3,000. Large sections had to be reworked. The seven-boat programme is now put at around £12.2 billion, more than 50 per cent above the original plan.

Individual build times tell the same story. From keel to commissioning, Astute took roughly 115 months; Ambush about 112; Artful, Audacious and Anson around 130 to 132 months each. Agamemnon’s steel was cut in July 2013. She was launched only in October 2024 and did not leave the yard until today - the longest construction of any nuclear submarine built for the Royal Navy. When her name was announced, the Ministry of Defence expected her in service in 2022. The seventh and last boat, HMS Achilles, was laid down in May 2018 and is now projected for 2028 or early 2029 after the October 2024 fire in Devonshire Dock Hall. From first keel to last delivery the class will have consumed close to twenty-eight years.

Later boats were meant to be quicker. They were not. Dreadnought absorbed people and hall space. The pandemic and stop-start funding kept the drumbeat slow. A yard that must now promise an SSN-AUKUS every eighteen months has spent a generation delivering one Astute every three to four years.

Boats in commission, boats that do not sail

The availability crisis is not a secret. HMS Ambush last went to sea in August 2022. She has sat at Faslane in very low readiness for more than four years and has been partially stripped of parts to keep her sisters running - a front-line nuclear submarine used as a store. HMS Artful has not sailed since around May 2023; by late May this year that already amounted to 1,120 days alongside. HMS Astute arrived at Devonport on 30 June 2025 for her first mid-life revalidation period after fifteen years in commission and will be unavailable for several years. HMS Audacious waited the best part of two years for a dry dock, entered it in February 2025 and has only recently come out. Anson, the one boat that had been doing real work, including the first Royal Navy nuclear maintenance period in Australia, has been in Devonport since May.

In 2025 the in-service Astutes together spent only around 300 days at sea. The last Trafalgar-class boat retired in 2024, removing the final buffer. On paper the Navy has six commissioned attack submarines, with a seventh in build. In practice it has spent long stretches of 2026 with none at sea. A 120-day blank in SSN presence is not a maintenance dip. It is a capability gap.

What this means for AUKUS

This is the industrial and operational base onto which the government has loaded SSN-AUKUS. The Strategic Defence Review promised up to twelve new attack submarines. Steel on the first British boat is due in 2027. The first Royal Navy SSN-AUKUS is not expected in service until the late 2030s. Exact numbers will not be confirmed until 2028. Reactors will come from the same Derby works that is already feeding Dreadnought and the tail of Astute. Construction will take place in the same Barrow halls that have just taken thirteen years to get Agamemnon to sea.

The stated aim is a continuous drumbeat and a larger flotilla. The recorded performance is the opposite. If SSN-AUKUS follows anything like the Astute first-of-class interval, “late 2030s” is an optimistic reading of a 2027 steel cut. An eighteen-month cadence cannot be willed into existence while Achilles is still unfinished, Dreadnought occupies the hall and the existing boats cannot be kept at sea for lack of docks, spares and people. Australia is building a new yard and preparing Submarine Rotational Force-West for 2027. Britain is asking the same strained enterprise to replace Astute, grow the fleet towards twelve and support an ally at the same time.

Ambition is not being matched by action. “Up to twelve” remains a phrase, not an order. Confirming hull numbers after first steel repeats the Astute habit of announcing a class and discovering the quantity later. Life-extending the older boats can only buy time by consuming the same Devonport docks and the same scarce maintainers. Sending Anson to Australia was the right AUKUS signal. Coming home to a fleet with no SSN at sea showed the cost.

A departure, not a delivery

Agamemnon is a capable design: some 7,400 tonnes, Spearfish torpedoes, Tomahawk land-attack missiles, and the endurance to stay down limited chiefly by food. The Royal Navy needs her, and it will need Achilles after her. UK Defence First has argued that Britain must be able to act alone in the Atlantic, protect the deterrent and the carriers, and sustain a real production drumbeat. That requires boats that sail, docks that work and an order book that industry can plan against.

This week’s passage down Walney Channel is worth marking. It does not close the 120-day gap in operational presence, and it does not prove that Barrow can build the next class on the timetable ministers have advertised. Thirteen years from keel to first voyage is not a foundation for twelve SSN-AUKUS boats. Unless the programme is accelerated, numbers are fixed and sustainment is treated as a warfighting task, Britain will enter the 2030s with a celebrated partnership, a handsome new hull on trials, and too few attack submarines actually atsea.