Stealth and performance improvement over the Mod. 0 Mk.8 gun. It is also known as the
Kryten gun, after the character in the popular UK TV science fiction series
Red Dwarf.
| 2001 |  HMS Norfolk F230 | Frigate Type 23 Duke class | First ship to be fitted with Mod 1, Mk 8 4.5 gun |
| 2008-oct | HMS Campbeltown F86 | Frigate Type 22 (Batch 3) Cornwall class | to Rosyth for a substantial refit by Babcock International. As well as a Sea Wolf missile system mid life update, a new Mk 8 Mod 1 main gun and Type 22 SEL, a major structural survey led to further unexpected work, delaying the completion of the refit until 20 Jan 2010. |
| 2008-dec-30 | HMS Montrose F236 | Frigate Type 23 Duke class | at Babcock until Sep 2009, for extensive refit programme, including Seawolf mid life upgrade. |
| 2009-may | HMS Westminster F237 | Frigate Type 23 Duke class | Entered HMD Devonport for refit until mid Mar 2010 with Babcock, to address Seawolf and its control system. |
| 2009-oct-09 | HMS Argyll F231 | Frigate Type 23 Duke class | to Babcock at Rosyth for an 11 month refit, including the Seawolf mid life upgrade returning to HMNB Devonport on 30 Sep 2010. |
| 2013-apr | HMS St Albans F83 | Frigate Type 23 Duke class | at Portsmouth for 15 month refit including Kryten gun and Seawolf system update. Rejoined fleet on 1 Aug 2014. |
Chilean Navy