Seaslug was the Royal Navy's first Guided Missile, and was carried by the County class guided missile destroyers.  The eight ships of this class formed two groups, HM Ships Devonshire, Hampshire, Kent and London were equipped with Seaslug Mk1.  HM Ships Antrim, Glamorgan, Fife and Norfolk were equipped with Seaslug Mk2, and later had B turret replaced with four Exocet launchers.  The latter group can be readily identified by the double antennae of their main air-search radar, the type 965.

Seaslug was designed as a shipborne medium-range area-defence surface-to-air missile; the project started in 1949 but it didn't enter service until 1962.  Its task was to destroy medium to high altitude bombers before they could release weapons (including nuclear bombs) aimed at RN warships. It was just supersonic and surprisingly accurate; some sources credit Seaslug with a single-shot kill probability (SSKP) of 92%! I have, however, established that the true SSKP of Seaslug Mk1 was 75%.  The use of four solid-fuel boost motors in a wrap-around configuration attached to the front half of the missile gave it a good acceleration and obviated the need for large stabilising fins (as were needed for the land-based missiles Thunderbird and Bloodhound).  Guidance was by beam-riding with an active radio fuze, and it carried a large blast warhead.
The cost of an individual Mk1 missile was approximately £20,000.

Even as Seaslug was entering service, an upgraded model was being planned.  Codenamed Blue Slug this was a faster, longer-ranged version that could carry a nuclear warhead.  The idea of using such a warhead was effectively prevented by the atmospheric test-ban treaty.  All the other improvements, however, were utilised for Seaslug Mk2.  These included higher speed, longer range, better (infra-red) fuzing and the use of solid-state components.  The SSKP for the Mk2 missile was 65%.

A typical Seaslug firing. Some Seaslug statistics. Seaslug in the Falklands.
Some Seaslug test firings. The three Seaslug firing modes. The proposed reactivation of HMS Kent.
A firing that went slightly wrong.   A Glossary of Seaslug terms. Proposed Seaslug armed ships.
Interception plots. Assessment of firings.
A few Seaslug pictures. The background story of Seaslug. Some Seaslug tales and anecdotes.
Seaslug and the Candle Flame. Seaslug myths and legends.
Early tactical thoughts on Seaslug. Questions...and answers.
The Seaslug tool chest.
Contact call! The ships of the County Class. Fuzes for the Mk1 missile.
Something different: Fireflash. Radar sets of the County class. Proposed fuzes for the Mk2 missile.
Details of the Type 901 radar.
Details of the Seaslug weapon system.
The DLG's Ops room.

Sources: TNA ADM 1/16467.

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Seaslug's stablemate -Bloodhound

If you have any photographs, information or stories about Seaslug, I'd be delighted to hear from you.

This page copyright SR Jenkins September 2002; reproduction without prior approval is prohibited.
Page last updated: 26th October 2021.
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