Tomahawk loadouts and the delayed Astute replacement

The 1998 plan reduced the attack-submarine force from twelve boats to ten while fitting the remaining boats to carry conventionally armed Tomahawk missiles. Those missiles used the torpedo tubes, so carrying them displaced torpedoes rather than adding a separate vertical-launch magazine. The first Astutes were expected to start entering service in 2005. HMS Astute was instead laid down in 2001, launched in 2007, and commissioned in 2010. Retiring older boats against the promised replacement timetable therefore exposed the force to a capability gap when construction slipped. Retaining Splendid and Spartan longer is proposed as a way to cover part of that gap, subject to their hulls remaining suitable for continued service.