HMS Ambush (S120): A Nuclear Hunter-Killer From Barrow to Brazil

Built at Barrow-in-Furness

HMS Ambush was built by BAE Systems Submarine Solutions at Barrow-in-Furness, ordered in March 1997 and laid down in October 2003, a long gestation typical of the complex Astute-class programme. She was launched on 6 January 2011 and commissioned on 1 March 2013 at HM Naval Base Clyde, the second of the Royal Navy's Astute-class nuclear-powered attack submarines.

A Reactor That Never Needs Refuelling

Ambush is powered by a single Rolls-Royce PWR2 nuclear reactor fuelled with highly enriched uranium, designed to run for her entire 25-year service life without ever needing to be refuelled, a remarkable piece of engineering that lets her stay submerged and on station for as long as her crew's supplies and endurance allow. She carries six 21-inch torpedo tubes capable of launching up to 38 weapons between them, including long-range Tomahawk Block IV cruise missiles and Spearfish torpedoes.

Maiden Deployment to Brazil

Ambush's maiden overseas deployment in October 2014 took her to the United States and Brazil, calling at Port Canaveral and taking part in celebrations marking the centenary of the Brazilian submarine force, a genuinely fitting piece of naval diplomacy for a brand new boat. She went on to take part in Exercise Joint Warrior and Exercise Dynamic Manta in 2015.

A Collision Off Gibraltar

On 20 July 2016, while surfacing during exercises in the Strait of Gibraltar, Ambush collided with the Panama-flagged merchant vessel Andreas, sustaining significant damage to the top of her fin, where much of her sonar equipment is housed. Repairs cost some £2.1 million, and her commanding officer forfeited a year's seniority for negligently hazarding the vessel, a costly reminder of just how crowded and hazardous the waters around Gibraltar can be for a submarine coming up to periscope depth.

Ongoing Service

By mid-2026 Ambush's absence from the water had become part of a larger story than her own maintenance schedule. She had not been to sea since autumn 2022, and by June 2026 was reportedly being cannibalised for components at Faslane to keep her sister boats seaworthy rather than working toward a return of her own. That month, all five of the Royal Navy's Astute-class boats, HMS Astute, HMS Ambush, HMS Artful, HMS Audacious and HMS Anson, were alongside at the same time: HMS Astute deep into a multi-year refit at Devonport that began in June 2025, HMS Artful last at sea in the spring of 2023, and HMS Audacious having spent the better part of two years waiting for dock space before finally getting into No. 15 Dock in February 2025. With the last Trafalgar-class boat retired from service in December 2024, the fleet no longer has a spare hull to absorb a long refit without leaving Britain's attack-submarine capability critically thin, turning what might once have looked like one boat's bad luck into a fleet-wide readiness problem.